I believe that in short and due time we'll find that much of those returns were 1) non-real due to inflation, 2) will crash back to historical means when we return to less strange monetary policies (such as non-zero interest, and selling at the end of QE), and possibly an effect from retirement/inheritances of baby boomers

Only time can know if I'll be right or not. I actually have a bit of a hypothesis that cryptocurrencies like BTC isn't actually productive right now, it's just wealth preserving and looks like it's "exploding" only because it's relative to a inflationary fiat currency.