You may not "make" money on old cars, but it sure beats the depreciation hit you take buying a new daily driver from the dealer. See what that's worth after 5 or 10 years.

I drove my road runner for 15 years and sold it for about 5 grand more than I bought it for. I figure I put about 5 grand of work into it over that same time. So net gain of zero and a lot of fun over 15 years. Not a bad deal at all when you are talking about a "hobby"