> But you could have a proof of stake system that requires exchanges to hold X% of their funds available, similar to the requirements for banks In Bitcoin's ca

> But you could have a proof of stake system that requires exchanges to hold X% of their funds available, similar to the requirements for banks In Bitcoin's case you can even do that provably and without trusted third parties: https://github.com/olalonde/proof-of-liabilities https://github.com/olalonde/proof-of-liabilities. I haven't worked on this in a while so there might be more recent proposals.