you can worry about your carbon footprint or not - your choice - but this is about as silly of a statement as they come. this is like being nazi in Auschwitz and going “well someone else would commit these heinous crimes so what’s the difference if I do it.” you do your part - that is what you are in control in and what you can decide on based on your beliefs. but to say “well shit, this plane gonna take off anyways so imma just jump onboard and take a couple of seats that are available” is not an acceptable argument