The two biggest risks to crypto are 1) government outlaws it, and 2) quantum computing cracks it.

Quantum computing will make all traditional encryption obsolete, all crypto currencies will crash to zero.  It's not a matter of IF the powers that be want to use it to crack crypto, but the mere possibility makes crypto a poor choice as a storage of wealth and the value will plummet very quickly to zero.

It is possible a quantum layer could be added to existing blockchain tech.  It's also possible the coins we own will go extinct and be replaced by quantum blockchain.