The secret is that liberals love to talk about him more than anyone else. And the more you tell these kinds of people "not to do something " the more theyll want to do it. So when liberals talk about how "dangerous" or whatever he is, theres about half the country who thinks its cool or edgy and votes for him out of spite.
If supposed Trump haters stopped talking about him for a solid 6 months after 2020, then its likely he wouldnt have made it past the primary.