It's a bit nit picky but the key to Simons system (or any system for that matter) is not that he wins more than he loses but that his net win/loss amounts are positive (ie he makes lots of money doing it).  I know it's counter intuitive but I looked at a few trading systems that had losing averages (ie lost alot more times than they won percentage-wise) but that actually made money because the many small losses were significantly less than the few huge wins that were generated (vice versa and obviously your account blows up pretty quickly).