I agree that cruise ships are an abomination in terms of energy consumption. But wrt flying, the whole "personal carbon budget" thing is a PR move by the major

I agree that cruise ships are an abomination in terms of energy consumption. But wrt flying, the whole "personal carbon budget" thing is a PR move by the major carbon generators to shift responsibility from themselves (who have the ability to make systemic changes) onto individuals (who don't). The planes fly anyway; business travelers make them worthwhile even if they are mostly empty. Your 100kg does not make an appreciable difference, and no significant percentage will stop flying even if most vacationers abstain. See in particular the flights that flew completely empty during early COVID so the airlines could keep their precious airport terminal allocations.