Actually, many supercar buyers are enthusiasts who weren't that rich before, but eventually got there.
Cleaning business guy, restaurant owners, transport company owner, many are self-made entrepreneurs. These people grew up aspiring to own one bedroom poster cars, and eventually realising their dream.
Rich guys buy "safe" cars like Rolls Royce, Maybach, or Bugatti if they want some speed. But some of their brats, using excess money would buy one for 2 or 3 months before deciding that they can't handle it, or get maimed/injured/killed in the process. That's why there is always these expensive cars in the second-hand market. To prevent one falling into burly business owners, Ferrari takes back their top-of-the-line (Enzo and La Ferrari)model if some "worthy" rich kids decided that they won't play with it anymore.