Usually with an IPO there is a 'road show' by the investment banks bringing in the deal, where those banks meet with prospective investors and talk up the issuer's business and prospects. After demand is gauged, a price range is set, orders taken and when the issue is released, shares are traded. Unsold shares are taken on by the investment banks bringing the issue to market, and then marketed to clients of the respective banks.

In the case of SPCX, Leon Skum has dictated an offering price of $135 per share, and many investors will choke on that price, given the highly speculative nature of the company (SPCX has lost billions each of the last two years). The investment banks will bring the issue, but will probably not offer to take on unsold shares, instead giving only 'best efforts' commitment. Certainly, lots of buyers will take shares at $135 because, well, it's a Leon Skum production, and well, buyers will golden, eventually.

My prediction: the IPO issuance will not go well, the big mutual fund complexes will hold back, retail investors will get burned, share prices will fall after a few days of froth, and Musk will look like the mentally ill idiot he is...