The fiat-based value of BTC is down over 80% from the Big-Time highs of late 2017:
(Q) Did (for example) a large number of bitcoins disappear forever?
(A) No, they simply passed from generally weaker players to "more serious" (long-term successful) ones.
Does Real Wealth Get Lost When Bitcoin "Crashes"?
and/or...
Does the chaos and "pain" create many new opportunities for various types of "hungry" people?
Does Real Wealth Get Created When Bitcoin Rises Rapidly? 
My answer:
You gain real wealth when you have an honest way to earn Bitcoins.