Because I "use up" three times the space. If you bought every seat on the plane and flew alone, you'd have 300 times the carbon footprint as someone flying coach, instead of it being divided among 299 other people.
So those luxury passengers on Emirates and the like who practically have a private room are where on that scale?
I was thinking “business class” meant three hops instead of one non-stop flight.
Something I like to think about once in a while for grins:
There are at least 500,000 people flying RIGHT NOW.
https://www.quora.com/How-many-people-are-in-the-air-flying-at-any-given-time