I hear stuff like this so often as a vegan. I get asked why I don't wear leather, since the animal was already killed for its meat, so I might as well make use of its skin. Just yesterday I got asked why I won't consume dairy because "the cows like being milked. It hurts the cow if they're not milked."
God forbid I try my best to reduce animal suffering. I know it's not going to amount to a lot if I'm just an individual making consumer decisions, which is why I don't treat veganism like that. It's not a diet or a clothing style, it's a demand for the end of animal suffering. And to that end I'll try my best even if it makes my life personally difficult or annoying.
The only way I've been able to explain veganism to carnists is to ask them if they'd eat a dead baby, or wear their dead mother's skin. But even that's not very effective. I don't know how to explain that animals are living beings who deserve life and dignity, same as humans. Because part of the problem I run into is needing to explain that humans deserve life and dignity. It's hard explaining to a typical American carnist that cows shouldn't be forcefully bred or used as a milk production factory when the same person believes homeless people all deserve to die.
level argument.