it also requires aesthetic needs to be met, social needs, and self actualization. for many people, those may require that you, for instance, master french cuisine, or eat your grandmother's lasagna, or just have hotdog and beer at the ballpark.
vegans have been around since the 1940s, and my guess is there are more now than ever, but the meat industry grows year-over-year every year. being vegan doesn't decrease the amount of meat dairy or eggs produced. it certainly doesn't reduce the amount of vegetables grown.
since vegan fare is pretty limited, i think the first thing is that vegans don't eat nearly as much fast food. they probably eat out less overall. which is going to require a lifestyle that carves out time at home to cook or meal prep.