Have you ever stopped and listened to how stupid arguments like this are?
Pretty much every living species is inclined to take the path of least resistance to achieve their goals. You might go for a nice stroll in the woods or a walk in the park, or walk to work in order to combine exercise and travel, but if you need to get anywhere quickly everyone will get in a car or on a bus, train or plane as long as the possibility exists.
No matter how many times you say that "you can stick to the ground if you prefer" or "dragonriding is still an alternative", in the long run everyone will default to flying by simple human nature so long as it is available. Sheesh, it's really not that difficult to figure out.