That, at least, is the story my (quite socially & economically progressive) mother tells, emphasizing grandad's integrity of belief over their deep political differences. (Which can be quite nasty—they went through periods of not talking during the Trump presidency). Whether, and how true that story is, I'm not sure
So she admired his commitment to his beliefs while being so angry at them she refused to talk to him.
I do think that this is a big problem with Trump (or Brexit in UK) - the sheer divisiveness, sides unable to even meet and work on a solution. A total paralysis from a parliamentary level right down to that of individual families.
In my family it didn't go quite that far... but my brother is utterly enraged in that he feels Mum and Dad [EDIT I JUST SAW THIS BIT THAT I NEVER FINISHED COS I WAS INTERRUPTED] voted in such a way as to take away his child's opportunities and, after hours of argument, we ended up with a subject that is taboo and gridlocked... a huge waste of time basically.
It might be pride! I wouldn't assume it's pride. People make immense sacrifices for their beliefs sometimes, and I am hesitant to deflate all that by psychologizing it as, you know, fear or aversion or some underlying personal failures.
I say "deserves it" because I think orienting your life around money is a pretty widely recognized failure mode whose best-case scenario, even if you manage to keep your mountains of gold, is spiritual emptiness. In other words, if there's a pot handle everyone knows is hot and you touch it and get burned maybe you had it coming.
So a sort of moral come-uppance; after doing everything right according to the rules of finance (but only those rules), playing the game seriously and playing it hard, to win, it looks as though it's all paid off. Until, on a whim, the merciless trickster gods of capitalism snatch it all away and having ignored the other aspects of life he has no other resource, no other value system by which to score his existence and demonstrate his worth. An extremely harsh lesson - I think the idealized version of this story is where the Scrooge character does win all... but realises the emptiness of this victory, and then after some kind of Damascene moment he repents and is able to change, use the money for good, make friends etc But what you describe is far more brutal - as life so often is.
I understand his circumstances are (greatly?) reduced, but he's not destitute, homeless right? I'm sorry to harp on this, but it really intrigues me, how did he deal with it? Is his attitude changed to himself and to others? Is he bitter or philosophical? Does he blame himself or others or luck or the game itself?