Why did fascism become popular in europe after ww1

Fascism started in Italy and spread to Germany.

It was sparked by : 

High unemployment (1921 in Italy and 1932 in Germany.)
Destabilized government in the wake of WW I.   Both countries were at the mercy of factional strife, coups, and street fighting.
Fear of Communism.   When the Communists came to power in Russia, they executed Tsar Nicholas II, cruelly bayoneting his daughters.   This sent a down every royal spine in Europe (many of whom were related to Nicholas.)  The wealthy also feared for their power and riches.   Communists were active in both countries, trying to get themselves elected or take the government by force.   Both Mussolini and Hitler exploited this fear to secure help from the wealthy and powerful.
Wounded national pride in the wake of WW I.  Although Italy was among the victors of WW I, it was quickly marginalized by the other victors.   It received none of the spoils of war and no voice in the armistice.   Germany of course lost the war, much territory, and had to endure the Treaty of Versailles which inflicted total blame and financial reparations
.Many war veterans from WWI.   The streets were full of experienced soldiers, jobless, often still armed.   They were ripe to be organized against other political parties.   Political disputes often spilled over to gunfire in the streets.   These conditions favored the most ruthless political party