Imagine if the U.S. dollar lost 3/4 of its value in a single year, and regularly doubled (and halved) in value. That's the reality of Bitcoin -- anything else is a fantasy, or, at best, a naive hope.
This is why it's not even close to dead and will continue to get flows of liquidity during boom cycles, because many others also see this regularity you've identified.
But imagine living in Argentina and working and saving your whole life just to see your life savings wiped out in a two week timeframe.
Or you get on some government shitlist and they freeze all your assets.
This happens over and over, and crypto can solve those problems.
do you have the same criticisms for the biggest equities in the US stock market?
Does it happen every two years? - obviously not
Are stocks intended to be currency? - no
Stocks also are attached to real property - ownership in a revenue / profit generating company and their assets. Crypto is only a vehicle for speculation.
A currency should not experience regular crashes or explosions of value. Assets are generally more volatile by their very nature.