Is it though? You can see on this app how a failure of the network could occur: https://www.btcsecuritybudget.com/

Tinker with the success/failure thresholds if you want but you get the general idea.

Peter Todd's idea to solve the problem may not be necessary. Maybe spacechains or some other similar solution can provide enough funding for miners, but I do agree that we're essentially gambling the most important asset on what is essentially a meme.