the exchanges that have been around for decades probably just made good investment decisions. i doubt that most exchanges are keeping all of the Bitcoin in a wallet. it makes sense to invest it, and tada, that's fractional reserve banking.
Discussion
Yes, exactly. Too much money/Bitcoin in storage tickles the custodians, they feel obliged to invest it.
One difference is that crypto exchanges reveal their fractional banking way earlier because transfers are happening on blockchain.
On the other hand, inter-bank transfers are hiding the fact that bank doesn't have the money.
well, if you're a nerd like we are, yes, but i'm sure that traditional finance insiders can also see such info