The people who study this tend to talk about it as if it were an aspect of health. It requires daily maintenance. It isn't like if you get x, y, and z then you will be happy and happy until death.
To your point it's not a video game objective. Happiness is being mostly happy and an inside job. It's not external. However happy people create other happy people.
Knowing that family is safe sound and happy and wants to see me as much as I want to see them is a pretty big boost, as is working towards a thing that I value and respect. It's not very exciting but it is happy.