Not as a confession thing but more like FYI: while I agree that the majority of people who gave up most likely weren't in it for the animals but for their own health, ethical vegans can also fail.
In my first try, I stayed vegan for a year. Was vegetarian for a couple of years before that. It was purely for ethics. I was completely dedicated. Tried to spread the word (I think I lacked tact big time for I lost a friend over it). I was enjoying every aspect of it (except social confrontations I handled poorly), I was eating very well, felt very good. I couldn't see going back as an option ever.
So why did I stop? Because I'm fucked up in the head. No need for details but mental issues prevailed, also conformism and fear of offending others got the better of me, and after a while I've come to hate everything so much I couldn't care. I thought everything was futile, horrors of humans would never stop. I lost my ability to care, not only about animals but everything in general. It disgustingly turned into hedonism as well. Very disturbing.
But like I said, this is not a confession type of thing. I don't want to atone for my sins. Just think it might be useful for other people in my situation to know they're not alone, if they ever read this. You don't have to hate yourself forever for losing your sense of morality. We're humans and can find ourselves in situations beyond our control at times. I never justified what I did, never for a minute tried to convince myself that it was right. But couldn't afford to feel the weight of it at the time.
I've encountered some arguments about ex-vegans at that time too. Guilt may be justified when you're aware that you're doing something wrong but one shouldn't get caught up in it.
I'm still hopeless about everything but I've been back for a while and I do hope this time it is for life. Though I've seen my worst and can't make promises to myself anymore. But I know right from wrong, and in any case I know what direction I should aim for.
Wonder how many ex-ex-vegans are there? I think it should be emphasized that while going back is a risk, coming back again is always possible too.