Founders Fund has investments in some of the largest internet age companies that exist.
Airbnb, DeepMind, Lyft, Facebook, Flexport, Palantir Technologies, SpaceX, Spotify, Stripe, Wish, Neuralink, Nubank, Twilio.
A call for them to move their money out of SVB meant putting pressure out on a massive percentage of SVB's customers by value.
It's not clear at all from news reports why Founders Fund put the call out. Fast Comapny's article notes that SVB had north of 32B in net assets before the run that Thiel's fund started.
IF FF had the facts wrong, this collapse would demonstrate the effect of a few poeple's outside influence in SV, and should be a warning to the broader industry of the power that these investment vehicles are wielding.