Its not buying it that causes the death, its that you've shown you want the meat, so the company is killing the animal to produce the meat for you to buy.
You want meat, they produce meat. You dont want meat, they stop producing meat.
what i wrote is that being vegan has not had the effect you are proposing it would. you are making up a scenario where it might work and asking why i don't think it would work in that scenario.
being vegan is literally about not supporting the meat industry, so i genuinely do not understand what you're trying to say. that one person alone being vegan won't make a difference? that not supporting the meat industry is the same as supporting the meat industry, which is demonstrably false? i don't know of a more easy and effective way for a single person to make a difference than to stop supporting it altogether, and broad change starts with individuals deciding to make that change.