Because of the oxygen which is also part of the 1000 t of "fuel". However, I think I used the wrong value anyway, for Starship instead of its booster, so x4 or

Because of the oxygen which is also part of the 1000 t of "fuel". However, I think I used the wrong value anyway, for Starship instead of its booster, so x4 or so. Doesn't affect the conclusion.