In game design, the Mastery Problem is the phenomenon that players will become too powerful in a game too quickly, becoming bored, bypassing variety for easier and repetitive gameplay, and crushing any new players who try to join, thereby ruining the gaming experience. Raph Koster mentions the problem in chapter 7 of his book A Theory of Fun for Game Design.
Possible solutions include lowering rewards for easy tasks as a player gets more powerful or making the game more accessible to new players by instituting a handicap system.