Let's separate out for a moment the rise of Marxism as an intellectual tradition from the actual mass movements that became revolutions. I think your question is more about the mass appeal of Marxism, and what circumstances drove people to the dangerous step of an armed uprising against the state.
Revolutions need kindling and a spark, meaning they need prevailing conditions to be very bad and a proximate cause to bring people to action. Conditions in St. Petersburg leading up to the October 1917 Russian revolution were just that bad. Around 2.4 million people lived in a recently industrialized city, and urban workers were often packed into cramped and unsanitary living conditions. The conditions were awful enough to make people desperate, and willing to take chances.
Life in the countryside was probably even worse, however. The end of serfdom had actually brought a decrease in peasant land ownership, and malnutrition and extreme poverty were widespread. Many peasants were driven into the towns and cities to look for work, and that’s where the revolution started.
On January 3, 1905, strikes broke out across Petersburg, with urban workers demanding better pay and conditions in the factories. United under the leadership of a priest named George Gapon, thousands of these working people put on their Sunday best and marched to the palace to present Tsar Nicholas II with a petition. It began:
"Sire! We workers, our children and wives, the helpless old people who are our parents, we have come to you, Sire, to seek justice and protection. We are in great poverty, we are oppressed and weighed down with labors beyond our strength; we are insulted, we are not recognized as human beings, we are treated like slaves who must suffer their lot in silence. And we have suffered it, but we are being driven ever deeper into beggary, lawlessness, and ignorance. Despotism and arbitrary rule are strangling us, and we are suffocating. Sire, our strength is at an end! The limit of our patience has been reached; the terrible moment has come for us when it is better to die than to continue suffering intolerable torment. "
The response from the Tsar was to allow then protesters to march to the palace, then order his soldiers to open fire upon them. Hundreds were killed, thousands wounded. The massacre immediately caused a backlash across Russia. Almost instinctively, hundreds of thousands of workers went on strike in response. Even after people returned to work later that month, the credibility of the Tsarist regime was permanently damaged in the minds of many.
World War I brought more pain and hunger to the urban Russian populace. Food shortages wracked Petersburg, and by February 1917, demonstrations over bread had escalated into full scale battles with the police. The Tsar stepped down, but the newly-installed provisional government could do little better than he had. And so the Bolshevik revolutionaries began, for the first time, winning real support in the workers councils ("Soviets") with their motto of "peace, land and bread."
Always a minority party, the Bolsheviks had not been one of the stronger elements in the provisional government. However, the deteriorating situation in Petersburg created an interesting and unstable moment. And there was a spark. A rumor was started the the Germans were coming to end the war by invading Petersburg by sea. The idea of occupation put many people, including many soldiers, over the edge. The Bolsheviks, who were gaining momentum at the time, also happened to be strong with the navy, and were in the right place to organize a decisive and nearly bloodless coup.
For a lively and polemical history of the conditions in Russia that produced a revolution, including a deeper dive into the conditions in the countryside, Trotsky's own book 1905 is available on the internet for free.