I think it is immoral to expect me to increase my workload by a ton through cooking, when I don't even have the time to take care of myself thanks to capitalism. Sadly, due to enormous subsidies meat is cheap, readily available and vegetarian/vegan options are scarce and overpriced where I live.
Added to the fact that the effort vs impact table is pretty much meaningless when you assess all the damage to the world that the rich are doing, it just feels like a gargantuan waste of my energy and resources, to not even move the needle.
And I get to piss off sanctimonious, preachy people like you in the process, win/win.