I bought a pair for $247.50 (10% off on running warehouse) to race in. I decided to try them out once or twice just for fun since I won't be racing anytime soon. Didn't love them, so figured screw it, I'll work out in them. I don't care about TM time, but I would rather race in Next%, and I already have the shoes, so might as well use them.
In my 17 years of running, last year was my first year ever that I ran seriously the whole way through the year without getting any injuries. This year, I'm 10 months in and once again haven't gotten hurt. I noticed back in 2019 that I get a bit less beat up if I do my workouts in older Vaporflys, so I've done all serious workouts in Vaporflys since then, and it's been by far my longest injury-free streak in my life. Do the shoes have anything to do with not getting injured? Not sure, but I do feel better doing them that way, so I'll keep doing it.
I don't have many major expenses, my car is paid off and likely has 100,000-150,000 miles left, I save 25% of my salary for retirement, and I donated about 10% of my salary to various charities this year. If I have enough left over to buy some fancy running shoes and end up using them for workouts in the absence of any racing, I think that's a pretty reasonable thing for me to do.