That's historically the least-persuasive argument for vegetarianism. The far greater threats are anthropogenic climate change, antibiotic resistance, accelerated pandemic evolution, land/water/air pollution, higher food prices, and less total available food.
The cognitive dissonance is very strong because people get violently defensive with their somatic lifestyle choices and will believe and do almost anything to extend them indefinitely. The only way out is leadership to tax, reform, and regulate excessively-subsidized meat agriculture that isn't good for public health.
If you successfully convince people to have vegetarian meals 1 times in a week.
You would make immeasurable more headway than mocking and guilt tripping people.
Campinas teaching people how to cook tasty and easy vegetarian dishes would go a long way.
But no, we will block the entrance to steak restaurant and call you names is the way to go...
I'm not trying to change peoples opinions by doing either of those things so I don't get the point of this comment as a reply to mine.
I also agree in a number of cases education is an important tool for making headway but I do also get that visible protest that confronts the issue you're tackling is also important.
I'd say wanting to eat to live doesn't require a justification.
In North America (which is the only area I'm even remotely qualified to speak on so will limit to that) it's entirely possible, and often healthier, to not have meat in your diet. The justification I'm talking about is about choosing personal enjoyment over animal welfare. It's easy to couch it in "you need to eat meat" like you've just done but vegetarians show that that's categorically not true in a many cases
Animal welfare, while laudable and under-appreciated, isn't the biggest problem with meat ag. It's fucking killing us slowly and may kill us quickly.
Most people are overweight. It's not about survival. It's 100% a choice.
It's pretty easy to understand that in at least North America our livestock handling practices cause a huge amount of suffering to animals for the enjoyment of people. But most people are able to ignore / justify that with a "well, it's bad but you gotta eat".
When presented with a group of people who make the choice not to eat animals / contribute to that suffering it challenges that justification and makes people very uncomfortable and in some cases angry. The easiest way to resolve this conflict is to mock those people and write them off as some kind of sanctimonious kill joys