Joe Rogan once stated on his podcast that he believes over 50% of UFC fighters were on PEDs, and other fighters have even stated they believe that possibly over 90% were at one time. With the new USADA run program that carries stricter punishments, and tests that can actually catch users however, the game has totally changed.
This is not to say there aren’t still fighters cheating, but it’s fair to say there are less of them than before.
It’s also the case that some notorious PED users are doing just fine in the USADA era. Alistair Overeem for instance might win the heavyweight title later this year.
Other fighters won’t fare so well, and the fighters on this list might not ever win again.