SpaceX are widely reported to be planning to raise $75Billion in new capital. It may seem small a % for the valuation target. However that is about 3 times previous highest raise of $29B when Saudi Aramco went public few years back. The market simply may not be that deep[1]
There is a good chance this one becomes the Wework of this decade. The valuation, amount being raised, cooling interests in AI, and middle eastern capital changing priorities, interest rate outlook for the rest of the decade. These are all strong head winds to overcome even when not raising the largest ever amount in an IPO.
That is not say that it is destined to fail, Elon is excellent salesman of vision when fundamentals are weak, There is no better proof than Tesla P/E .
It is by no means clear this would be successful or not. The valuation, funds being raised, future growth potential are all not based on just SpaceX core businesses which would have been an easy sell.
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[1] i.e. it could be still under-subscribed even if everyone buys into the vision, growth projections, is comfortable with valuation gets fully onboard including retail.
Even in this best case scenario SpaceX would have to sell at the lower end of the target range or go even lower and still end up being short matter what, because there could simply be not enough money in the market.