do you think convincing him is even possible? You're the one that knows him so i'm not gonna pretend I have the answer to that.
My friend's kid's mom is literally a flat earther, and she was your run of the mill democrat a few years ago. She voted for Obama twice. She got with some far right dude about 5 years ago and now she's all gun carrying pro-Trump and thinks Obama's going to hell (I'm not even sure her reason). She's always been an easily influenced dunce though. There are probably a couple more left leaning people I know who would be right wing given a change of environment.