I'm one of those people who was made vegan by another leftie! It took literally years of patient, open, honest and non-judgemental conversations and a lot of self-criticism. I actually owe that person a lot, and I'm incredibly grateful to have had them in my life. So it can happen, and people can appreciate it.

I want to preface the rest of this by saying it isn't supposed to be apologetics, just my honest take. Food is kinda my thing, I spend a lot of time thinking about how and why people make the food decisions they do. Carnism is a brainworm like any other. It's heavily pushed by industry, widely adopted by society, and strongly enabled by governments. If anything it's probably one of the more resilient ones, just because of how deeply food ties in to identity through culture, family, history and memory. Everyone has a favourite comfort food, or a meal that brings back fond memories. That shit works on a biological level and the industry absolutely knows how to hijack it. Abandoning it all actually takes a hell of a lot of effort for most people, who can't even seem to manage cutting down on soda. It takes practical lifestyle change, psychological, and to an extent, physiological, rewiring. Logically, I agree with you; if you're a leftist, you should be vegan. People don't generally make decisions like that logically though.

It's also the hill I'm furthest from dying on with regards to my social circle. I've met enough vegans who see it as a shortcut to "being a good person" without actually doing any of the self-crit necessary to arrive at the decision organically. I've also been around enough otherwise switched-on, generally cool lefties who eat meat but get squicked out by even seeing it uncooked. And yeah, the secondhand cognitive dissonance hurts. But I know which one I'd rather hang out with.