Near-immediate gratification is one of the satisfactions of games. Not necessarily “instant,” but you get to see investments pay off visibly in a short time, rather than needing steady, daily effort for years. (Ha, and this used to be an MMO blog.)
For example, your retirement account generally moves in the right direction, but compound interest takes years to pay off. You make the right decisions and then wait for very gradual doublings. It’s worthwhile but very slow, even when it moves quickly in an up market. Whereas your idle game takes you from selling lemonade to making millions in hours or days.
In-game farming takes seconds, not until harvest season. Mining, cooking, smithing a sword? Same. You move directly from cause to effect, without waiting for the process in the middle. Exercise yields visible progress towards strength, dexterity, and endurance every time.
I spend a lot of my real life time setting up lengthy but rewarding processes. Being able to defer gratification is important and valuable, one of the greatest and simplest keys to long run success. But danged if that gratification isn’t really deferred.