Eh, I think there are several reasons to favour the empirics we have on the subject over anecdotal experiences, which are going to be coloured by problematic biases (toupee fallacy, etc).

When we look at the data on the subject, both in terms of shorter term RCTs looking at biomarkers and longer term observational data, vegan diets seem non-inferior to the other top-tier dietary patterns we see for lifespan and healthspan (med, lacto-ovo vegetarian etc).

That said, I’m sympathetic to the view that with currently available foods one does have to be more mindful of diet than when on an omni diet - I think that’s true. But when an omni dieter looks unhealthy we just say “that guy looks rough” and when we see a vegan who looks unhealthy we say “vegan diets make you look rough”.