All of them have a fraction of the hashrate of Bitcoin leaving them extremely vulnerable to 51% attacks.
Not to mention they all trend towards zero against #BTC.
Discussion
I think the on and off ramps in #bitcoin ecosystem are far lower hanging fruit than hash rate vulnerabilities.
Agreed, that will be the thing that is attacked. However, POW is a winner take all game meaning that smaller coins will always suffer from vulnerability to 51% attacks.
Bitcoin does not need fiat on or off ramps. It is peer to peer money that cannot be stopped.