whereas if you didn’t consume it, someone else would.

There is more than one person on the planet. There is more than one person acting responsibly. It adds up. "Someone else would do this bad thing I am about to do, so it is okay" is also a very weak defense.

you’re solution of lowering consumption globally

Where did I say that this is the solution? It is an easy and effective immediate action people can take. Or they can spend their time telling themselves that they are alone and nothing matters. You are advocating for the second option.

it seems it would take a lot more work to make sure everyone isn’t eating more than a certain amount of beef than it would to ensure only a certain amount of beef gets produced.

What is the argument here? Work != emissions. And I never said that an authority should control individual consumption. I said that individuals living unnecessarily wasteful lives are part of the problem and take some responsibility. But you go so far to even try to legitimise taking as many flights as you want, so this discussion is pointless anyway.