You're probably right, if you're buying new.
I once read about a strategy that made a great deal of sense to me, and that was to buy a 2-3 year old used car from a new car dealer, and sell it after 2-3 years to a private party.
There were all sorts of good reasons for that, some of which may no longer be valid, but some of the reasons were that a 2-3 year old car still had a lot of value but was at the end of it's steep price depreciation curve, and that the new car dealer didn't actually know how much the car was worth, they just knew that every day it sat there was another day of insurance they had to pay for, and sort of more proof to them that the car was not worth much. Also, by buying from a new car dealer, the car was probably in pretty good shape, the worse cars they had gotten rid of, the rest they had fixed up and cleaned up at rates that you or I couldn't get.
Because of that, with good negotiation, you could, in a sense, capture much of the profit the dealer had just made by giving the former owner of the used car a terribly low resale price followed by selling them a high priced new car.
They just made 20,000 by cheating the former owner on both ends of his deal. They don't know how much the used car is worth, but they are scared of it sitting there, and if you know how to price it, value it, and negotiate for it, you can get them to go very low on the price just so they can move it off the lot. You could in fact buy it for far below market rate. That was the theory then. And my own used car purchases showed that to be reasonable.
The claim was that by buying so cheaply a good used car from a dealer, you could sell it in 2-3 years to a private party at a good market rate, but probably very close to what you had paid for the used car 2-3 years earlier.
So... This strategy has actually worked out very well for me. And kept me in some very fun, relatively high end convertibles, starting with a Saab Turbo 900. Buying used cars from new car dealers seems to be a winning strategy.
But you have to remember to flip them. And that's been hard for me to do, in part because like an idiot, I drive too many miles to work, and have no time for selling cars to private parties. But if you're going to put a lot of miles on cars, I think you do need to either flip them or drive them to death, which is one reason I recently bought a low end econobox.