The real point, for me, is not so much "Trump could have done better by investing in index funds", it's "Trump's business underperformed the market".
And, yes, underperforming the market over 30 years or so isn't proof of anything much; he could just have been unlucky. But for the exact same reasons, the fact that Trump's a billionaire isn't proof of anything much; he could just have been lucky. (He was: he inherited a lot.)
The only point I'm making is this: the fact that Trump is rich is not very good evidence that he's a great deal-maker. He's rich mostly because he inherited a fortune; someone who had inherited the same fortune and just put it into the stock market would now be richer than he is; what (admittedly limited) evidence we have of his business skill is that he's done worse than the market over the last few decades.
He might still be a great deal-maker. Or he might be a pretty terrible one. All I'm saying is that I don't see evidence that he's particularly good.
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.
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