I think you will find, when you look into the life of Karl Marx, that it often was the other way around: Marx was often forced away from writing theoretical works, in order to make money, to feed his family. This answer will be based in large part on Sven-Eric Liedman's amazing Marx biography, A World to Win(2018, Verso)

Marx was the son of a civil servant, a comfortable petty bourgeois, if not outright bourgeois family, in the, at the time of Karl's birth, recently made to be Prussian Rhineland. He fell in love with the most beautiful girl in Trier—according to Marx's own account, so take it with a grain of salt—Jenny von Westphalen, and as a young man, he left his home, to study law at the University. His time as a student is when we first see the handsome "Moor," as he was nicknamed, have trouble with stitching together a functioning private economy. Marx was a true man of life, with all it entailed of entertainment, food, wine, beer, etc. and the young man often asked for allowances, loans or pre-deposits of his inheritance, in his letters to his family. And the whole law thing didn't really work out; the young Marx was more interested in poetry, and philosophy, and then radical philosophy, and then... the young Marx as we know him, had come to be.

But one cannot be a student forever, and when Marx had received his doctorate from the university of Jena—(in-)famous at the time, for practically handing out diplomas to anyone who bothered writing a politely worded letter—the young man needed to find work, as he had bills to pay and a family to feed. Doctor Marx returned to the banks of the Rhine, and set up shop as a journalist at the radical newspaper Rheinische Zeitung. But Marx, a radical, was often at odds with the Prussian police, and he was not a popular name among many parts of the power that be, so his newspaper was often censored, and Marx was dragged into court, in which he, since he had studied law, defended himself, and some of his colleagues, and his newspapers ardently. But to no avail, and following complaints from the Russian Tsar, in 1843, the newspaper was closed, and the Marxes left for greener pastures in Paris, the shining home of radical thought.

In Paris, Karl's beloved family still needed a roof over their heads, and bread on their plates—"For talk does not make men full"—so once again, Marx picked up the journalist's pen, and now also the editorship, of the radical newspaper Deutsch-Französische Jahrbücher. It was in the Paris time, we see some of Marx's first theoretical writings also appear. Texts like "On the Jewish Question" was first published in DFJ. as was "Introduction to a Contribution of Hegel's Philosophy of Right" in which the famous passage about religion as the opium of the people appeared. Read also my answer here. So one could also say, that the development of theory wasn't opposed to Marx's "real" jobs, but often, as also happened later, was a part of the job. When the DFJ. collapsed, Marx moved offices to another radical German newspaper, Vorwärts, the namesake of the later newspaper of the German Social Democratic Party. The Paris years are generally thought of as the happiest of the Marx family, at least the most worry-free. It was also in Paris, that Marx's first two children were born: Jenny Caroline(1844) and Jenny Laura(1845) and where Marx would meet his life-long friend and collaborator, Friedrich Engels. But we shall return to him, and to the pockets of the Engels family estate, later.

It was also in Paris that Marx started taking interest in political economy, and where the Hegelian dialectic for real was put on its feet, so to speak. All while Marx was working as a journalist and editor, he also wrote the Paris Manuscripts, though they weren't published in his lifetime, and the Thesis on Feuerbach. But as would be a theme for Marx, there is always a neighbouring monarch, dead set on changing things for him. This time it was the Prussian king who asked the French to give Karl the kick, and the reactionary interior minister, François Guizot, closed Vorwärtz and send the family into exile.

Then the family, with two small children, and a Jenny who had just given birth, stood without home. Marx had had his citizenship stripped, so they couldn't return to Prussia, and France wanted them gone; they ended up in Bruxelles. A dark time for the Marxes, who never could find themselves quite at home in the comparably small city. From Bruxelles, Marx for the first time visited England, on a trip with his good friend and compagnon, Friedrich Engels. The two also collaborated on writing a book, what we now know as The German Ideology, but were unable to find a publisher. Marx had also promised Belgian authorities—who were weary of taking in a twice-exiled radical—not to publish anything about contemporary politics. Instead, Marx had published another book, to help make a little money, and "dunk"—as the young "peeps" say—on Anarchists; The Poverty of Philosophy was published in 1847, and Proudhon was put in his place. Marx also worked with underground radical movements, and together with Engels wrote and published The Manifesto of the Communist Party in 1848. Another small coin was made through the work Marx did for the organisations and in publishing these works. In Bruxelles, the 3rd Child, Edgar was born, in 1847. Edgar would grow to become perhaps Karl's dearest child.

In 1848, the Marx family returned to Cologne. Revolutions swept across the continent, and Marx saw an opportunity to return to Germany, and help in the struggle for freedom and democracy. In Cologne, he opened the newspaper Neue Rheinische Zeitung, a clear hark to the radical newspaper that he had worked for when he was first forced into exile. This is perhaps the most famous period of Marx's journalistic career, as it was his most radical and most publicised newspaper. It was helped financed through the inheritance Marx had gotten from his father, but it made some money on its own as well. Again, Marx and the staff was harrased by the police, and once again, Doctor Marx was forced to defend himself, his staff, and his newspaper in court; an opportunity he took to only further critique the Prussian institutions. Was it clever to double down? Perhaps not. What it did result in, when reaction won out in the revolutions of 1848, he was ordered to leave the country, and in 1849, him, a pregnant Jenny Marx, and their three children, ended up in London.

London would become the final home of the Marxes—despite attempts from Engels to get them to move up into the North and out of the city, perhaps closer to Manchester where he lived and worked—and it is the London period most people think of, when they think of Marx's family life. Marx, once again, set up shop as a journalist. This time working as a European correspondent for the American newspaper, The New York Daily Tribune. Marx did however also put in labour with the labour movement, organisational labour, and his own studies of political economy. But Marx would write for the Daily Tribune, with pieces on European politics, on imperialism, and on philosophy, sometimes book reviews. The Marx family was by no means a wealthy family, and the various shopkeeps would often knock on their door, asking for their money owed. The clever young Edgar, who ended up speaking English with a London dialect—nuture vs nature—contrary to his mother's somewhat stiff and formal English, and his fathers "wery noticable Jerman ackscent," would at times lead them astray, by telling them that "the man upstairs" wasn't home. But money was tight, and Marx often even pawned his clothes. In London, the fourth child was born; Henry Guido, nicknamed "Foxchen" or "der Pulververschwörer" since he was born on Guy Fawke's Night, a young boy. But the child was never healthy, and always hovered between life and death, and in 1850, Karl and Jenny lost their youngest child. Marx was besides himself with despair, the loss of their child hit the family hard. Marx wrote to Engels, about how Foxchen had been laughing and playing, and minutes later, the child entered into convulsions that would take his life: "The thing happened quite unexpectedly." And about how both he and Jenny missed his company, and that his absence "at this particular moment, make us feel very lonely." And Marx lamented the injustice of healthcare in bourgeoisie society; kids died due to their parents impoverished situation, since both doctors and medicine were outside the reach of the poor.

But the grievances didn't stop there. In 1851 a fourth child was born, Jenny Eveline, nicknamed "Franziska." The child was however, as the young Guido, sickly, and in 1852, contracted bronchitis; common particularly in the working poor districts of London, due to the bad housing, and, writes Jenny Marx: "For three days, the poor child battled death. She suffered horribly. Her small, lifeless body rested in the little room; we all went out of the room into the street, and when night fell we made our beds on the floor; our three surviving children lay with us and we cried over the little angel who rested, cold and white as chalk, next to us."

The Marx family was hit hard, and it seemed they only approached a pit of bottomless misfortune. 1852 was an annus horribilis for the family, but it looked brighter in 1853, where there was even money, for a "real" Christmas, as Jenny envisioned, having been brought up with the paraphernalia of the German Christmas. They had money to spare, Marx's work as journalist paid off, Engels had tried working as a writer himself, since his father wasn't too happy about funding the radical escapades of his son, so the Engels fortune wasn't as much help as it had been at times in Paris and Bruxelles.

And let us shortly address the Engels "furtune":