You’d probably have greater success challenging the “XKCD guy’s” assumptions if you adopted a less belligerent tone. I don’t know nearly enough to verify who’s right here, but some things that strike me as questionable:
The most fuel is spent relatively low in the atmosphere.
This is consistent with most fuel going into producing kinetic energy.
1 - accelerate to the Moon—from 8 to 10 km/s
Generate a delta-v a fraction of the one you needed to reach orbit, in vacuum, with an engine with a higher specific impulse than that of the Saturn V’s first stage, for a small fraction of the launch mass. Yep, shouldn’t take that big of a rocket.
You’d probably have greater success challenging the “XKCD guy’s” assumptions if you adopted a less belligerent tone. I don’t know nearly enough to verify who’s right here, but some things that strike me as questionable:
This is consistent with most fuel going into producing kinetic energy.
Generate a delta-v a fraction of the one you needed to reach orbit, in vacuum, with an engine with a higher specific impulse than that of the Saturn V’s first stage, for a small fraction of the launch mass. Yep, shouldn’t take that big of a rocket.
It is seriously more complicated than that. Same for returning to Earth orbit.