20,000 launches is 11 Starship launches a day for 5 years

It's an unsustainable rate and even if we do get to that rate it'll wreck the planet

Why is that unsustainable? You need to present an argument that is more than just "large number! wave hands!"

It's just like the arguments used by anti-renewable energy forces here on Earth. "Large number (of PV modules and wind turbines and batteries)! Unpossible!"

And no, that launch rate does not "wreck the planet".