There is some middle path - ie buying that beamer, few years old, for say 25% of the original price. Not because of some immaturity, need to compensate for something missing in life, just a desire to have a good car that does on the road exactly what one wants, whenever one wants and covers all one needs from it. Sticking with it for 10+ years, having it serviced at good unofficial mechanic, so it costs +-same as crappy cars people buy new for much higher prices. Which means simply not caring about the cost, in face of overall added value to life.

It brings long term happiness. Satisfaction. Its just great. One of best investment in quality of life I ever did.

Oh absolutely. That BMW was a used 2011 328i with a manual transmission. Great car and if I had kept it like you suggest I would have been smart. But I had to buy some other dumb used cars before I learned my lesson. Now I’m rocking a used ‘08 M3 to drive into the ground. Put 50k miles on it. Looking forward to the next 100k.

The decay slope of happiness depends on personality. I still feel glad I splurged for expensive stuff I really liked ten years ago, and still like now. Part of it is emotional inertia, but it's probably also correlated with the fact I don't do impulse buying, am wary of advertisements and thoroughly research prior to parting with money.

There's absolutely nuance. I think it's like you say, the mindset. If you purchase something because you want something that's "nicer than everyone else's", you'll be unhappy. You're inherently fighting a losing battle. Not only that but a petty battle.

If you instead, similar to how you describe, invest in something that you want to hold onto for a long time, that's a much better proposition. I have one expensive pair of boots. But I love them. I've had them for years. I treat the leather and polish them fairly frequently. I get them resoled. I expect they'll last me the rest of my life. Couldn't be happier with the purchase.