I've had debates with vegans on something similar:
I'm not vegan, I'll never be vegan. That's a complete non-starter for me.
What I have done is reduce my meat intake from 2/sometimes 3 meals a day to 1 meal per day - occasionally (less than once per month) two. Once Lab-grown meat is a viable alternative on cost/taste/texture, I'll be all over that. I still won't be vegan. Even if I reach a point where no animals are harmed from my diet.
I believe it is far easier to convince 1 Million people to do this than it would be to convert 100,000 people to full veganism. A Million people doing this would save Billions more animals per year than 100,000 vegan conversions and maybe even in itself convert a few of those people to full veganism along the way.
They're never interested. It's all or nothing. Black or white. Vegan or Animal killer. They usually have issues with lab grown meat, as well.
It's as though they're a member of an elite club and membership is more important than actually saving animals.