New, more inclusive version based on all the comments I got on the first one I made. I am sad that people being rude about our beloved pets is such a universal experience.
This is the best AITA because on the actual matter at hand I'd say he's kinda right (ish), $4900 for a week of work is really good money and they can always celebrate later. He should have obviously talked it over with her first but still. What makes him an asshole (or just like, a really really weird person) is every other detail that is tangentially mentioned.