Silicon Valley Bank failure could wipe out 'a whole generation of startups'

my sympathy is with them but please someone explain why companies were putting millions in banks beyond FDIC limit with almost no interest. Could have managed it themselves in a brokerage laddering treasuries or hired someone to do so. This is what big corps do and with interest rates so high seems a no brainier.Would at least think their investors would have insisted on it.

Maybe focus more on turning a profit than burning millions on operational costs and endlessly raising cheap VC money every month?