As a player gains mastery of a game they will often seek greater challenges which provide rewards different from those they sought after when they were less masterful.
In the case of, say, a time trial racing game, you perfect every corner until you can’t get any better, and then you start looking for things like hidden shortcuts that are risky but allow for greater reward for greater skill. If the game sets a goal of the shortest time, players will bend and break every rule they can to get the shortest time possible and do speed runs.
Most games obviously aren’t just timed runs, but in almost every game with a stat than can be tracked, a player can optimize for that stat. Moreover, in many games designers will intentionally put in these “hidden shortcuts”, where a very skilled player can reap a huge reward – or optimization. These systems are often hidden or left at the very end of games so that new players don’t become frustrated by thinking they should be able to perform these difficult feats too early in their process of mastery.