SX investor here: the combined value of SX is well up on the private secondary market post-acquisition. It was value accretive, in very real dollar terms.

Even if Starlink had more than a few tens of millions of customers, China mobile has 900 million subs and is worth around $250 billion. ULA was recently valued at about 1 billion. SpaceX might be possibly worth 50 times as much or maybe even 100 times as much. Falcon nine is the world's workhorse rocket, but it's just not that remarkable, and starship is utterly unproven to launch to orbit and land both stages. Starship has a payload capacity problem that must be solved to even get to the point where launching 15 refueling missions would be sufficient to get a starship to get anywhere beyond Earth orbit.

It looks like the plan is to IPO with a small float (in relative terms) and get all of the retail investor Elon fans to lineup for the rug pull.