I had that realization with another habit, in first person. My hands can do so many things yet I choose to do this repeatedly.

That said, these habits don't usually develop as a choice, they're a sort of shield protecting us from deeper issues, formed during difficult times in our lives.

For example, there's girls who gain a lot of weight after being sexually abused, because being seen as less attractive makes them feel safer.

This is why it's so difficult to quit, they're complicated and contradictory.