I think it's being a bit forward-sighted to assume in any reasonable timeframe SpaceX is going to suddenly enable more/better spacebound telescopes, or that we shouldn't safeguard our existing capabilities until we can ensure that is true.
It is commonly argued that "everyone has a right to clean, affordable drinking water", and yet New York City and China and India and etc continuously pollute waterways because business has been prioritized instead, for better or for worse.
Those facilities have resulted in lots of discoveries. But Kepler wouldn't have been such a success without lots of follow-up observations from ground-based telescopes (e.g., measuring spectroscopic radial velocities to confirm exoplanets). It's likely that many HST (and eventually JWST) studies rely or will rely on data taken with ground based facilities in order to actually interpret the data. Pardon the pun, but space based telescopes don't exist in a (scientific) vacuum. They have unique and impressive capabilities, but they don't stand alone.
I don't know how to measure some objective ranking of the benefits of terrestrial astronomy vs satellite internet services - I doubt there's any way to quantify those two things sensibly.
I _do_ note though, that while the existence of telescopes on the ground doesn't threaten the existence of satellite internet, satellite internet _does_ threaten the existence of ground based astronomy. Doesn't seem "right" that SpaceX(or Amazon or other constellations) can just say "Sucks to be you, we're going to fuck up your entire field of study because we think we can make a buck here".
Pretty sure we shouldn't just let Elon and Jeff decide here, without letting orgs like the IAU at least have their say, and put forward an argument against it...
More like: "Sorry to interrupt your observations, but we are trying to kickstart a space-based civilisation here".
I'm sympathetic to astronomers (I have a telescope myself), but I'd much rather go to space than just observe it.