Hm? Plenty of them did back in 2008. They were only insured uptm to $100k back then, it's up to $250k now but anyone who has more than that in the bank, which plenty of companies do, is sitting on a pile of risk. So then you withdraw your money from SVB down to $250k and then everyone else doing that - you have your bank run.

I don't disagree with you. Bank runs can still happen even with the (successful) FDIC backstop.