Two good rationalwalk pieces on the SVB situation
rationalwalk.substack.com - The fall of silicon valley bank
rationalwalk.substack.com - Fragile capitalists?

Long story short:
Apparently it was common practice for (at least some) tech startups who receive a cash infusion from venture capitalists to dump these funds into SVB to be held to handle payroll. Apparently, the $250K FDIC limit wasn't a concern to these startups (for whatever reason).

Might a whole bunch of such start-ups not meet payroll next week due to SVB's failure?
Should there be a bail-out, nominally to protect all the 'little people' who work at the start-ups, and thus stop a wave of failures that will kill innovation?
Are there more banks like SVB, who did nothing illegal (imprudent is a different issue), and will there be a giant sucking sound as funds are extracted out of all but the "systemically important banks" (SIBs)?
Apparently Mr Ackman of Pershing Square thinks so, and that a bailout is needed.

rationalwalk argues that the original VC's literally have a stake in this. They can inject more capital into their strong firms, and let the weaker ones die. Capitalism at work. Furthermore, he points out that there was no reason for any firm to have way over the FDIC limit plunked into one bank. They could have had a ladder of treasuries maturing every week and plunked just the weekly burn rate amount into a bank (or a few banks).