What's the point of an IPO? Show problematic institutional investors the door and replace them with disorganized public investors? Attract talent?

Seems like if the company is really doing great you'd want to retain ownership. Raise from bonds or something. Put simply, if it's valuable why would anyone sell it?

A lot of VCs had money locked up in SpaceX, like, portfolios going back a decade or more had some sort of investment in SpaceX. The IPO gave them an exit.