7 bill sent to Binance and random VC is plausible at least, but it sounds like the money vanished (it doesn't vanish, someone somewhere took out large sums of money).
7 bill sent to crypto is hard to believe, and sounds more like laundering, but the cash reserves should nonetheless have a paper trail.
4 bill will not vanish, or it may have never existed, or he's lying and it was moved to a Cayman acct(s) somewhere.
If it never existed, then FTX was operating more like a bank - dollars only work because they have a paper trail and we can keep printing new ones. Try cashing out your savings, you might be able to. Now try everyone cashing out - there is no money for it.
With a real bank OFC there is a lot of scrutiny and supposedly you have to keep track of assets and liabilities but there is a large degree of fudging it, plus they can always get loans from the unlimited central supply if they have an immediate shortfall...
Which might be what he's looking for i.e. a bailout via printed money, which would allow investors to withdraw funds and OFC send inflation sky high...