Exit liquidity? I feel like it would be a lot easier to raise $100b from a few private investors if you had reason to be confident that you were gonna make a self-improving cash printer. If, however, you weren't sure what you were gonna actually be able to pull off and saw a plateau or drop coming you could use an IPO to generate hype and get some liquid cash and then dump your position on retail and institutional investors if it doesn't work out. Why don't they don't rely on private investment and profits? I don't have the information to verify this for sure but one theory is that they don't think there will be much more private investment or cash flow.