Problems with a bitcoin monetary standard

I have been a bitcoiner for a few years now. I am currently in an advanced (Keynesian) macroeconomics class and it has made me question some things.

If there is a bitcoin monetary standard in the future… how will businesses get credit/loans to operate their business? Without credit businesses would innovate much much slower, productivity would go way down. Less employees they can hire, etc. It would be much harder to get a business off the ground, and take so much longer to build up a business than if you had cheap credit. (I understand the consequences of cheap credit)

Hence there must be bitcoin “banks” or exchanges that distribute value between savers and borrowers.

Since bitcoin is decentralized and no protection from a central bank, I can imagine there would be bank runs all the time. The loans to borrowers would be very illiquid and the liabilities of savers who deposited their bitcoin would be very liquid. This is what happened during the Great Depression.

Hypothetically, all the bitcoin depositors would pull out of the exchange and the exchange would become Insolvent.

Therefore lending/credit would be pretty much non existent in a bitcoin standard? Therefore output and productivity would greatly go down? Therefore standard of living goes down?

Can someone please walk me through this and prove me wrong? ????. The Keynesians are getting to me.