A lie can be a short-term way of handling the world until you're ready to deal with the truth. "F*ck it all, I don't care any more" is just such a lie. You care, you know you care, and you know that lying about it isn't going to work very long. But the utility of the lie is that maybe it will let you keep going until you are ready to deal with the truth.
It doesn't work for long. Maybe it will work just long enough.