I think a lot of people are hoping that Trump moderates his stance on different things. You have to hope so, as his full package of white nationalism, misogyny, racism, targeting of Mexicans and Muslims, economic protectionism - is pretty horrific.
I don't think he's the same as Hitler, but his policies are dangerous. Also, abandoning climate change is the real nightmare, and there are predictions that temperatures could rise by 7 degrees, if the Paris accord is abandoned.
There are unpleasant reminders of the 30s, and we all know where that led.