I know plenty of people who are reasonably frugal who still go for the new car, though I think they view it as more of a slightly risk-averse heuristic than an optimal decision. I think most of them recognize that with planning, effort, and a bit (but not a ton) of luck, they probably would do better used.
The risk averse heuristic goes like this: identify a car with a reputation for value, purchase under a buyer's plan, take very good care of itfor the useful life of the car. These aren't the people who show up in a shiny new car every few years - they often keep the car for 15 years or more.
Like I said, it's a bit risk and effort averse, since with a lot of research, careful evaluation (including a mechanic inspection), and a bit of luck (more the absence of bad luck), you can definitely beat the above strategy by going used. It's a lot of effort, though. Personally, I did all the things you're supposed to do, and still ended up with lots of $$ repair bills, so I'm no longer interested in used cars. I understand that I got unlucky, but I'm just done.
I suppose I'm also particularly convinced by the argument that people generally don't sell good used cars, since I'm one of those people who hangs onto a car until it costs me more to own it than replace it.