ICOs have done the same, creating a massive amount of shadow convexity
(1) Locking up ETH, raising ETH's market cap
(2): Creating wealth out of of thin air in the form of new tokens
But also:
(1) Recycling that same ETH back into the market b/c they have trouble selling to fiat
(2) When then goes on to invest in other ICOs.
This is a massive systemic risk IMO. It's easy to hide shadow convexity in a bull market, but in a bear market it comes cascading down.