Earlier quoted context omitted.
The part where you say "cash out" is hilarious. There is no cash in it. You only get to keep the bits. Any cash comes from buyers and if there is any attack all the buyers are scared away.
This is the terrifying thing about a bug in one of these systems or some other kind of attack. The whole network can suddenly drop to zero in the blink of an eye.
1: https://medium.datadriveninvestor.com/itcoin-unhackable-it-h...