Yeah, it's just a mistake here. He and his parents were just circus performers, not particularly wealthy. He didn't have money of his own. Later on we're told that he had money either from insurance or money from an account his parents had started saving for him that Lucius had been directed to invest so now he had a small fortune of his own.
Though that could also have been a story Bruce made up so Dick would take the money.
But regardless, obviously Dick and his parents didn't actually live in a house because they travelled around with the circus, and Dick's parents couldn't have afforded to buy the circus like Dick did.