I think the old cars may be like boats. The two best days are when you buy it, and when you sell it.
The key difference is that a boat, in general parlance, is rarely used. It sits in the driveway under a tarp. It gets towed to a lake maybe 3-4 times a year, for one day at a time. And each time, there's prep-work before sailing it, and shutdown work (such as cleaning things) after.
For me, an "old car" would be new enough, relatively speaking, that it would be a plausible daily driver. I live in a warm climate and have no family, so neither winter-durability nor passenger space are important. If I were braver, I'd daily-drive a liter-class motorcycle, and call it good. But I'm... prudent (euphemism). A good daily driver by my reckoning is something like a 1970s Porsche 911 when an engine swap, hopped-up to massive torque. Or a BMW 2002 - remember those? - also with an engine swap. Or an Opel GT with a stretched wheelbase and big block Chevy engine. Basically 1965-1985 era cars, with very extensive power mods. And they would all be driven on the order of 5000-8000 miles annually, including in traffic... yes, Los Angeles stop and go traffic.
On a completely different note, the other day I test drove a 2008 Corvette... base model, with a stick shift. The experience was starkly different from that of my Mustang GT test drive! Putting the 'Vette in 2nd gear, 2000 rpm, and flooring the gas... it makes a very impressive concerted push. Not like a Tesla Model-3 Performance, but incomparably more assertive than the Mustang. It also felt lighter, more responsive overall, more communicative, more.. involving. With the Mustang, I felt like a passenger who happens to be seated in the driver's seat. With the Corvette, immediately upon jumping-in,
I was driving it, instead of it driving me. It felt like a bigger, stronger but slightly less agile version of my venerable 1991 Miata.
What next? I learned that if the aim is a modern car, with modern car conveniences but modern car baggage, the choice might very well be a C6 Corvette... maybe base model, maybe Z06. But if I want the nimbleness and elfin lissomeness of a Miata, with the sheer thrust of a Tesla, then I'm going to have to build such a car. It isn't going to be at a dealership or a used car lot.