Most of the ones I know, even the super active ones, either look very unhealthy, are often bloated & gassy, or struggle with undesirable body composition issues (still not happy with abs, etc) & they tend to blame age.

There are quite a few recovering vegans out there who talk about their health completely collapsing after some nunber of years despite all sorts of efforts at supplementation & rather extraordinary lengths to "do things right."

From what I've seen, the difference in outcomes between vegans & vegetarains who cheat once in a while vs those who don't is pretty dramatic. It seems that the human body is pretty amazing & a little cheating can go a long way.