If humans stopped eating meat, millions of animals would still be killed by predators, illness, parasites, old age, accidents, etc.
If I don't murder people, people will still get murdered. Therefore it doesn't make a difference if I choose not to murder people?
Kind of an interesting thought process. It seems like the assumption is "I'm doing it, so it has to be fine".
The problem with thinking that way is people have flaws, and if you think like that you'll just take it as a given whatever you're doing is already correct and never fix any personal issues.