I think he had his feelings hurt by these snubs, but to align with the anti-immigrant side was odd. I think that, plus he understood the Republican "money in my pocket over all" values rather than a more complex "be a decent person" valueset. The former was more clear than the latter, and clarity beats morality any day.
Oh yeah, he also made what - $500 billion dollars? - by aligning with corruption and cronyism.
edit - also, as I've become older, I find myself saying more and more that my dad was right. I guess he may have realized the same thing after he alienated his family. It turns out maybe there was some wisdom in the old emerald mine magnate papa (</s>) and any criticism of how workers are treated, or markets manipulated, or harm caused to millions - it is just woke haters.