There was a time you could build a cool car and get appearance money from car shows if you were a well known builder but I don't think there was ever a time you could make a living this way. Ed Roth used his show cars as part of a money making business. Each year he would come out with a fresh show car. He was not after trophies or appearance money, he got the right to set up a booth on a primo spot in the display hall and sell T shirts and accessories. He might make several thousand dollars a weekend this way. The cars were also featured in the magazines of the day. Because they were famous show cars. Possibly him buying full page ads in every magazine every month had something to do with it. All this publicity made it worthwhile for a model company to pay him a royalty to produce plastic models of his creations - cars and monsters. So you had Roth building show cars, leveraging them for publicity to sell the T shirts at shows and thru magazine ads, plus revenue from models, for several years he made a good thing out of it. All the parts working together. Then times changed. Monster shirts went out of fashion in favor of drugs and sex references, a direction Roth refused to go. Show cars went out or turned into caricatures of outhouses and dump trucks, another place he didn't want to go. He got more and more into custom motorcycles which the car magazines wouldn't touch, and the model company dumped him. So the whole thing collapsed. The point is, the show cars did produce revenue indirectly but they were part of a large complex business. When times changed the whole thing fell apart. Getting divorced didn't help. He was one of the few that made money out of building show cars. The others were show promoters who featured their own creations. Again, the show cars were only part of a larger business.