> How did they not become spacex/starlink

You need to go big first with the rockets.

If you have the rockets, everything else is easy later on. Collect millions from others to launch the satellites in the meantime.

And if you don't have rockets, you use SpaceX, like GlobalStar does.

Leo/Kuiper was launching satellites on SpaceX as well.

Only after a shareholder lawsuit

Before Falcon came in and drove down launch costs significantly putting lots of satellites in low orbit you need to replace constantly was a bad way to design a satellite network. It still has some issues like the continuous ongoing cost where the traditional providers' satellites would last for many years before needing to be replaced.