Banks generally cannot make these kind of directional bets, and the Gamestop saga has shown that it's very risky for short interest to get too high against retail excitement. So if an IPO is heavily overvalued, the level of pressure required to bring it down immediately may not materialize for structural reasons. I made a modest amount of money from SPCX falling, and I'm sure some hedge funds made much more than me, but I and I expect they would have stayed far away if short interest had been higher.