What's unique about SVB though, is that despite it being a relatively large regional bank, a handful of its customers - tier 1 VCs have enough clout to force a bank run. These VCs have created a situation where their entire portfolio of companies depend on SVB, and as a result if they say "Get out of SVB" they can cause massive disruption. What's really funny about this though, is that these VCs -aware that this is the case - don't decide "Better be super careful about dealing with SVB and slowly diversify to de-risk this massive systemic risk to their industry. No, instead what they do is they execute the exact bank run they know will massively damage their industry.
To put it in historical context, this is like if JP Morgan, instead of gathering institutional leaders and co-ordinating a calm and orderly response to a crisis had run on to twitter and screamed "IT'S ALL GOING TO ZERO GRAB YOUR CASH NOW".