Drinking
There was a time that drinking carried with it a thrill. The flash of acceptance by his peers, the risk of being caught.
Then it became a habit. An expectation, though not a conscious one. It was just a part of everyday life, like the friends he no longer really connects with, but finding new friends seems complicated and lonely.
Now it is no longer drinking. It is alcohol, and he needs it to not feel sick, to not hate himself.
Maybe he should quit. But that strikes him as uncomfortable. Better just to not think about it too much.