Why do you think people stop playing minecraft with age ?

Those who stop playing I believe it is because they are already saturated with the same thing all the time, when you have mastered something, and cannot find many more reasons to go further, it ends up being something tedious to repeat the same thing if your creativity is not very great, so they end up going to different games in search of new experiences.

If you are playing singleplayer it really can get lil bit boring...