People will always do things the most efficient way in games, even if it is not the most fun way.
That is a hard statement to argue with because we know that people do behave that way. But it seems like the problem is overstated, that people generalize from the some to the many, or even to all. The problem is that we prove the statement true using a small set of people and then use it as if it was true of everyone. The ambiguity of natural language lets us get away with that.
Still, the idea that people will act against their own interests to earn rewards in video games seems pervasive in the drive towards "balance." If sorcerers beat the dragon faster than wizards then everyone will play a sorcerer, if wizards are faster then everyone will play a wizard. If mining makes more stuff than gathering then people will mine, if gathering makes more stuff then people with gather. If actually playing an engaging game makes fictional currency faster than dutifully pressing 'Q' every 15 seconds then people will play the game, but if pressing 'Q' is more efficient then undoubtedly that is what people will do, even if the gain is only marginal.
I haven't seen any evidence that any of that is true. A very small number of people will radically alter how they play for marginal gains, and a slightly larger number of people will complain that it isn't fair to them because the way they prefer to play is no longer the best way. A very disproportionate amount of attention is paid to the people who are on top and to the people who feel like they should be on top but that the system is rigged against them when more attention should be paid to giving everyone who plays the game a wide range of choices so they can play the game their own way and have fun doing it.