It's funny, at first I thought he was merely in it for self interest. Maybe Russia offered him a lucrative deal, or the pee tape is real. I mean, I'm sure that's still a major motivator, I just wasn't sure Trump had conviction in anything but $$.
Then you get to his "relationship" with Kim Jong Un, or white supremists. Those aren't relationships that typically could benefit a business man. Public racism leads to even CEO's stepping down. Meanwhile he slams wealthy China, and befriends North Korea. Again, not a seeming business savvy move.
Things like that have to be his true beliefs. Belief in racism. Being in awe of dictators. Things that won't necessarily give him a direct pay day, but are things he believes in nevertheless.