People know cars like those will never be made again, and quite a few people who grew up with 90s cars are now old enough to have the disposable income to buy them.
Ultimately new gas cars will be banned. Many governments have already expressed the desire to ban them. That is one of the major differences from the mechanical watch market -- but even in that market, values of vintage watches are going absolutely nuts. In the car market, vintage cars will be the only ICE cars one day.
If you have spare garage space, one of the best things you can do is buy an older unmodified sportscar that had a good reputation in the 1980s or 1990s, hold onto it for 10 years, and sell it for a massive profit. Something like a 911, or Supra, or MR2, or maybe even a Miata.
Electric sports cars will have better performance, and be familiar to everyone in a few years. Won't most people want a car they can also drive to work?
I can imagine it will be like a neighbour who owned a very old (1930s?) car. Maintaining it was a hobby, and actually driving it on public roads was something he did only a few times a year.
Ferrari was dying until Fiat bought it. Lamborghini would have died without Audi. Porsche would have died multiple times without VW - and relied on VW components throughout its entire history. American sports and muscle cars were made by the Big Three, and used V8s made for other vehicles.
Without that investment, it will be impossible for sports car makers to make vehicles that meet contemporary roadworthiness standards.
Not to mention that you won’t be able to sell them in the EU, California, New York, and China beyond 2035. Doesn’t leave much of a market.
Maybe there will be a residual business selling ICE sports cars to Middle Eastern plutocrats in 2035, but those plutocrats may have more urgent things on their minds given the long-term demand for oil and gas is headed one way.
If all I can do with my petrol car is drive it to the track and for special events, I think I would be content enough. I don't need the thrill of the sights and sounds of racing on my commutes, and I believe motorsport is the only exception that isn't trivial.