I double checked to make sure, the top two cryptos (Bitcoin and Ethereum) own 81% of the crypto market. Bitcoin has 68.1% and Ethereum has 12.9% . Regardless of your perspective, that does show monopolitistic tendencies even in unregulated markets.

The point being, when does a monopoly/oligopoly become unhealthy for market competition? Because there werent government regulations on what standard oil could do until it became too powerful, and then government (not the market) broke it up with anti-trust laws.