Plato was born into old money. I always knew he came from a privileged family but I had not paid much attention to his biography. There is little information about him but he could be likened in status to Cato the Younger (without the big pickle jammed up his backside). In the Middle Ages, 'Plato' was said to not be his birth name, but was a nickname that he acquired from his wrestling instructor Ariston due to his broad physique or broad face. He had been named after his grandfather, Aristocles, according to Diogenes.
Most introductions to Plato's works will not mention the controversy about his name. There are several issues wrong with the story. First, Plato is a common Greek name and second his father's name is also Ariston. None of Diogenes' sources survive. Diogenes is the only early source for this anecdote. There are also many who still tell the story of Plato's name as though it were a proven fact. I found a nice article in "Classical Philology" by James A Notopoulos called The Name of Plato. I suppose it is best that he remain Plato since, if his name really was Aristocles, people might confuse him with his pupil, Aristotle.
Seriously. Especially people who are up late at night speed reading for an exam. Not me, of course. I would never do that.