Take people who are unhappy with their lives, their current lot, their future prospects. Tell them that someone else is responsible for their fate (immigrants, liberals, people of color, people in cities, whomsoever) and that he can make *their* lives painful ("I am your retribution.") and you have a follower.
I have a visceral reaction when I drive past someone's house with the full Trump display (flags, signs, etc.) but I can continue on. The thought of being unable to get away from those people...(!)