You're wrong, plain and simple. It's laughable that you cite Paypal, which have actually just paused and further purchases of crypto currency until an indeterminable date, so are currently looking like they want to back out of the market. Besides that, Paypal were allowing people to trade cash 20 years ago, long before crypto came into existence and they flourished without it all that time. Heck, even Elon Musk got rich from the money that paypal was bringing in from transaction fees and they had everything perfectly manageable on arrays of servers. Financial institutions don't need crypto in the slightest to function, banks have been running even longer than Paypal and successfully moving money around - much faster and at cheaper cost (at least to the institution. Crypto is a threat to their profitability, so they are likely adapting to incorporate or subdue the effects if possible.