I post this hesitantly because it's probably some subtle bias (possibly selection/observation bias), but: the vegetarians and vegans I know personally, they all look borderline unhealthy and seem to lack energy in a subtle ways. Also, my wife sometimes watches cooking vloggers, and I can usually tell at a glance whether the particular tuber is a vegan/vegetarian blogger or not: the ones who are also give this impression of health problems and lethargy. This observation makes both of us hesitant to go vegetarian (though we try to reduce the amount of meat we consume).