I have no great justifiable or practical means to explain why I don't keep cars very long in comparison to you. I get bored with them. I find them to be more than a form of A>B transportation. I enjoy the engineering. I enjoy chatting with others who appreciate the same. I enjoy the thrill of driving in a sportier manner. I haven't subscribed to the keeping up with the jones. I don't really know anyone in person who is interested in cars with a sporty nature like myself so I'm not keeping up with anyone. I can see where that theory comes into play but I don't feel like I fall into that. In most cases people never notice my car and I'd rather it be that way. It is by nature rather understated. It is in those few times when I meet up with someone at a light or a parking lot who also appriciates cars where we can chat and appriciate each other's vehicles.
You're a car hobbyist. Nothing wrong with that. My brother falls into the same camp, just he's not flush enough to buy new cars as often as he might like. Actually, he says his Mark VIII has better fit and finish, and is nicer to drive, than many newer cars. Not surprising given that it was $42K new back in 1993 (he bought it used for something like $17K). He might not mind a newer car eventually, but it'll have to be markedly better in most areas than what he's driving.
For my sister on the other hand, a car is simply a means to get from point A to point B. She'll happily ride a bus instead of drive if one is available. Actually, she did exactly that. She started driving a few miles to the park-and-ride instead of driving all the way to work. My sister probably represents the vast majority.
I've never owned a car so I don't know what camp I might fall into. In truth given the congestion on public roads I probably wouldn't see much point to getting anything beyond an econobox (an electric econobox because I really like the concept of EVs). Fast cars (including electrics) might be fun to drive and all, but there are scant places where you can open them up without risking at least a traffic ticket, or even worse, colliding with one of the incompetent minions on the road these days. I think that's why I love cycling so much. A bike is one of the few vehicles which you can "drive" flat out, and nobody notices. A velomobile would be even nicer (some of the faster ones can
cruise at 40 to 50 mph with a strong rider).