That's inconsistent with the fact that ground-based astronomy is able to build large and complex optics pretty cheaply, which is the basis for this complaint to

That's inconsistent with the fact that ground-based astronomy is able to build large and complex optics pretty cheaply, which is the basis for this complaint to begin with. By leveraging these things, you could build an inexpensive space telescope. No one has done so because it has only recently become fairly cheap to launch stuff. JWST is such a terrible example of a space telescope done with good cost constraints, BTW. And that kind of infrared astronomy which needs gold-coated mirrors and 20 Kelvin operating temperatures can't be done on the ground at all. We were discussing near-visible optical instruments and comparing to ground astronomy.