I have a very simple algo (like 30 LoC) that is currently performed 9x S&P returns on >100k in initial capital. Granted, this is over a relatively short span of time and it doesn't observe the requirements to be part of Quantopian's contest. However trading live, it is doing significantly better than any back-testing I've done.

There's nothing preventing designers from putting their own money in. Contest winners get profits in addition to whatever they invest themselves, on the condition they share the algorithm (I think closed source?) with Quantopian. That being said, Quantopian probably has enough information to reverse-engineer at least the main ideas of anything you share, given they can observe the orders made and probably also your network requests.