I think the question of "overall" can be broken down by age of the project starter.
I think guys in their 20's, especially nowdays, maybe 10% of them actually have the ambition to start something like a project car. Then I think of that, maybe 15-20% actually will see it through. Most of my life I have seen nice cars absolutely butchered by internet trained millenial hacks, then advertised as "too many projects" or "want something different" or "not enough time to finish" as they realize you can;t be a hack, t's not like making a peanut butter sandwich, precision and knowledge are required. The fast and the furious REALLY hurt a lot of 80's and 90's cars, the number of sawed up interiors, painted up interior panels, "cut springs" with no other suspension adjustments... people took nice cars and simply trashed them out.
When you get into the 30-40 year old crowd, I think the number goes up a lot. Except a lot of them can;t afford to actually do it. This is the age people will sit on a vehicle for a long time thinking they will get to it. Sometimes they do slowly, sometimes not. But for the ones that don't, the second middle aged owner probably will.
I can;t speak to the group closer to retirement. Seems for every guy that works on cars there are a dozen that talk about it, or sit on a car that should have been fixed 20 years ago or sold, but "I know what I got" until that car is a rotten shell and the owner that has had it for 30 years can;t see the rust, they still see the memories when they parked it.
For instance: (not mine!)
Posting this for my dad. Selling a 100% true roadrunner. Same motor, Trans, rear end. Have most all original parts for it. 318 motor, 3 speed. Needs Total Restoration. I can give you his phone...
www.facebook.com
This sort of thing is common in the midwest. People with big dreams and an inability to let go of memories and such will have a car they drove in winter in the 70's "put away for retirement" and discover salt doesn;t car if you washed it off or not 40 years ago, that "a little bit of rust" isn't fine to ignore for 40 years, that cars from that era were never designed to last this long, and the midwest is not the southwest.
Some people have good intentions. Some people have grand plans, and good ones to boot. But they don;t take action, maybe for finances, whatever. I know a guy that has had a car in storage with 19k miles on it since 1980. Always tells me what he will do with it. He is 68 now, and so far has not done a single thing. His kids will get it I am sure.
I see this, and in my mind the stuff I work on is stuff I know I can work on(well, until recent inflation, making me reconsider things lately) because no way will I sit on a project and hopes and dreams for decades, I would get depressed! Better it went away and out of sight and move on with life then to constantly be schemeing about when I can start or how.
But then, cars aren't investments to me. I don;t really care if it might be worth xxxx amount more in 20 years. In 20 years I will maybe be dead. In 20 years it will look like this poor roadrunner above. I see the "holding on" crowd in mostly the retirement age group. The 90's I think blew a couple of their minds with "investment" opportunity and stuff they sold for $100 being worth 1000 times that, if only they knew! And some simply apply that to everything so you get the above and stuff returns to the earth while they die with their dreams unfullfilled.
