You're making a similar mistake treating it as fait accompli that SpaceX will tank between IPO and some future date, but that isn't a given either.
sure it's not a given, but I certainly am not confident enough that it won't happen to bet my money in it, which I would automatically be doing if it was admitted to the SP500
SpaceX is not worth $1 trillion, when most of that valuation is based on xAI being worth far more then their already dominant position in the space launch business.
It's more about sidestepping the waves of market manipulation.