I think that a metaphorical approach makes a lot of sense, as in "they don't see themselves as humans, they see themselves as superior to humans, and they see humans as their prey". This stacks well with the near global mythos of dragons, with many legends that speak of dragons as superior beings who are often associated with great wealth, power, and mystique. I could very easily see these people associating themselves with dragons.

It doesn't hurt that there's a lot of media and fiction that supports dragons as "lords" over humans, in turn sort of reinforcing the association between dragons and power. From Smaug in The Hobbit, to the queen from Sleeping Beauty, who turned into a dragon; there's the fact that dragons are a literal and figurative symbol of power and authority in Game of Thrones, and even in Japanese media, the "Celestial Dragons" pretty much define a low-key version of the Cabal in the world of One Piece. Dragons have a common theme of power and mysticism applied to them in stories from around the world that go back for centuries, at minimum.

The idea makes a lot more sense than the idea that the ruling class is some sort of literal lizard race that can shapeshift or otherwise disguise themselves to fit in with the rest of us.