Vegetarianism is plagued by apostates as well as hypocrites:

[A]ccording to a 2005 survey by CBS News, three times as many American
adults admit to being “ex-vegetarians” than describe themselves as
current vegetarians. This suggests that roughly 75% of people who quit
eating meat eventually change their minds and return to a diet that
includes animal flesh. It seems that for most people, vegetarianism is a
phase rather than a permanent change in lifestyle.

Hal Herzog and Morgan Childers created a small survey to find out why people abandon vegetarianism.  The results seem obvious at first: “Health” is the most common reason, followed by “hassle” and “cravings.”


Now take a close look at the smallest bar: “ethical.”  Many people become vegetarians for moral reasons, but ex-vegetarians almost never change their minds about the morality of meat-eating:

About half of the respondents originally gave up meat for ethical
reasons. Yet only two of our ex-vegetarians said changes in their views
of the morality of killing animals motivated their decision to resume
meat consumption. In fact, most of the former vegetarians were still
concerned with animal protection and the ethical issues associated
with eating animals.

This result should shock anyone who thinks that moral self-deception is a big deal.  If people use moral reasoning to justify whatever they felt like doing anyway, why do ex-vegetarians cling to their original moral perspective?  A little rationalization would allow them to have ideals and eat them, too.  So why don’t they?