Your brain's not your own.
It goes to the employer during 10 hours of intense concentration plus two hours of intense commute: time lost from the point of view of your productive ambitions, time well spent from the point of view of the roof over your books and guitars and microphones and realistically-last-on-the-list head which ostensibly contains the brain which emphatically is not your own. Got all that? Me neither.
Where does your life go? It goes to someone else.