While the great depression was indeed a factor, the far bigger one was the conflict between socialists revolutions and the governments repressing them.

I'm gonna talk about my country here. Italy after WW1 was deeply indebted, with an economy barely running. Its massive army demobilized meant hundreds of thousands of unemployed ex-soldiers.

On the other hand we always had a very strong socialist party. Anarchism as a concept originated in Italy with Enrico Malatesta and Giuseppe Fanelli and was later formalized by Mikhail Bakunin, close friend of the two mentioned individuals. Antonio gramsci is another great socialist thinker that lead the anarcho-syndacalist movement during the red biennium.

In 1919 and 1920 Italy saw wave after wave of strikes in the industrialized north, together with a surge of farmers strikes as well reaching even a million participants. Towards the end of 1920 workers started to occupy factories, in particular the FIAT plants in Turin and Milan. Contemporary observers were convinced Italy was at brink of revolution and in a way they were right.

In the mean time the "fasci di combattimento" kept fighting the insurgent red menace. These were usually groups of ex-soldiers fighting socialism because of its stance against nationalism. They felt Italy was betrayed first by the allies during the peace conference (the famous "vittoria mutilata" mutilated victory) and then by its own people, namely the socialists, that fought against Italian intervention before and during the war.

The rebellions of the red biennium did not manage to gain momentum and were eventually stopped. This opened the door for fascist repression. Workers union were forcefully disrupted, the socialist party dissolved. A couple of years after the fascist "took power" with their march on Rome.

I put "took power" between quotes because it was not a violent coup, like we often hear. Mussolini was appointed by the king and had the support of the industrialists and the church, more than happy to support his anti-socialist and militaristic views and to avoid further social conflict. The march on Rome was simply a charade put up to make it seems Mussolini managed to win his revolution.

Source: Fabio Fabbri, Le origini della guerra civile. L'Italia dalla Grande Guerra al fascismo. 1918-1921 (it's in Italian I'm sorry)