No one claimed that it was. Buying a mansion and shitposting on twitter isn't exactly the sign of being a failure, is it?

By all measureable metrics, I'd assume that his life is better than 90% of people that started life in the same socioeconomic class that he did.

I didn't say it does, but the clear fact of the matter is that there is literally no evidence that being rich leads to being miserable.

People saying "money doesn't buy happiness" don't realise that money doesn't bring unhappiness either. You can't use that statement for asserting that some rich person must be unhappy.