@mcc An alternative explanation for much of the same results (which I think is more likely because it doesn't require the collective action of a capital strike), is that the investment is all real and intentional, it's just vastly misdirected from the point of view of general economic growth.
Billionaires don't care about their absolute wealth (they can't spend it all), but only about relative wealth (compared to their peers). And so all the investment gets misdirected into long shots, because getting lucky with those is the only way to significantly move up the rankings.
Investing in normal things can only get you a normal return. It's just treading water as far as they are concerned.