Just to add to these two excellent posts, three facts about humans.
1. They're angry.
2. They're stupid.
3. The angrier they get, the stupider they become.
Fuelled by their abject poverty and humiliation on the world stage, Germany was a seething country and people took that frustration out on Jewish people. As Hitler knew, it's very very easy to manipulate public feeling and mob mentality.
In fact, given the same economic circumstances as 1930s Germany, you could create a similar mob mentality here in relation to Muslims.