I believe dragons must have flown once, but after they developed a more earthbound lifestyle their wings devolved into the stubs we see today.
According to the theory of evolution that could only happen if having shorter, stubbier wings was more advantageous (thus, creatures with them would live longer and reproduce more often than other creatures) than having wings that could fly. Which is probably not the case.
However, modern society turns evolution upside down, especially medicine. As random genetic changes (or defects, or whatever) cause changes, medicine and technology adapts to supplant for harmful changes (anything that isn't caused by a virus or disease, such as short/long sightedness, requiring glasses, an overly enlarged diaphragm that requires surgery to correct, etc, I think is possibly due to such genetic changes accumulating and being passed down because medicine has ensured they will not limit a person's ability to pass on their genes).
Thus, if dragons stop flying, their wings would not "devolve". However, a random mutation might cause dragons with shorter, stubbier wings, and since this is a modern society where there is no pressing need to fly away from predators, such a gene could propagate. Even so, as there would be no advantage, the majority of the dragon populace would still have large wings.
And that, in a extremely convoluted nutshell, is part of my views on evolution, based on a class on it I took one semester.