It depends at least partially on how much they're going to float. I think SpaceX is only planning about a 4% float, so even at $1.5T they only need around $60B. Which is a drop in the bucket.
EDIT - but that's just the IPO, I wasn't even thinking about how much insiders will want to sell after the lockup ends...
EDIT - but that's just the IPO, I wasn't even thinking about how much insiders will want to sell after the lockup ends...