Of my current circle....
I have two friends who, before I knew them. were vegetarians for years before switching back to meat-eating. I recently found out that a male coworker was also a vegetarian for eight years before reverting back to meat. That's three people that I know who are ex-vegetarians.
Not counting myself, I only know one other vegetarian/vegan.
That's a ratio of three ex-vegetarians to one practicing vegetarian (in a very non-scientific survey.) It makes me wonder how many other ex-vegetarians are out there.
I haven't asked these people why they went back to eating meat. My two friends, both female, are sensitive animal-lovers. I've gathered that it was because of "health reasons" and I suspect one was advised by a doctor to eat meat for protein reasons.
Being a vegetarian is more than just a diet choice. It's a statement of values, whether one wants it to be or not. People don't usually become vegetarians because they don't like meat....in that case, they just don't eat it.
It's hard not to be disappointed in people who became vegetarians and then went back. Particularly when it's for "health reasons." There are many other sources of protein, iron, etc. out there that do not have to be dependent on meat. I think it shows a weakness of principle and conviction. I hate to say it, but I have more respect for people who have always eaten meat than those who make the vegetarian choice for years and then just give up.