Truuue, fast food chicken is fake as fuck anyway, it has already been properly imitated.

Even better, when I feel as a lazy fuck I throw the nuggets to the microwave for 30s and eat them with ketchup. They aren't "raw" so it's safe to do so, suck it meat tendies you can't compete.

Sure, but that's wrong and used for convenience because the terminology got muddled early on. That was the original definition (i.e., no eating animal products), but the Vegan Society who created the term changed it not long after (in the 1940s?) to include avoiding exploitation generally "as far as is possible and practicable". That's because veganism is an ethical movement that sees this exploitation as fundamentally wrong. There's still a note about this original definition at the end, of course, because a dietary term is largely how it exists in the minds of non-vegans.

What you're referring to is a plant-based diet(er) (or "strict plant-based diet" if you want to be really clear and beat marketing buzz). Calling a vegan "someone who eats meat no more often than a month" in the sense of how vegans use the term would be like defining someone who's anti-dog-abuse as someone who kicks their dog at most once a month.

(Edit: Notably, "vegan diet" is used among vegans, but because it's a diet that comes as a consequence of being vegan, not because following it makes you vegan.)

TL;DR: That's a definition used mainly among non-vegans.