Vegan Circlejerk

Sadly you missed a very important point in your argumentation: Cats are being kept as pets. They usually have a good life for simply being cute and easy to handle.

Keeping them to eat them is a downgrade (nothing changes except that they live shorter - assuming you butcher them in a normal way, not with a baseball bat which might cause a slower and painful death). When doing nothing, that downgrade doesn't exist, so on average the life of cats will become better.

Pigs for example either are being kept in mass-production factories (really the most fitting word for those, animals there only exist for their materials) or they are being kept in a more ethical way where they can go outside whenever they want, get better food, can run around, are much healthier, ... .

This is an upgrade (they live longer, healthier and happier). When doing nothing, that upgrade doesn't exist (as commonly), so on average the life of pigs will become worse.

As customers we have the power to show the mass production industry that we don't agree with their actions - you also do that by not buying any meat / milk / eggs / ... . But while this decreases the amount of miserable lifes it does not offer an alternative - animals either get born under those conditions or not at all. Meanwhile when supporting farmers who care about their animals, you offer an alternative - farm animals finally get to live a happy life.