Does everyone who practices guitar ends up a great musician? And if they don't, but only practice guitar to relax, would you consider the time "wasted"?
I guess you could approach this kind of question from a risk/probability point of view. Not everyone who practices guitar becomes great at it, but some do, so if you practice guitar you expose yourself to a potentially big upside (assuming you actually want to be a great guitar player).
I can't think of a potential upside that you expose yourself to by watching TV (other than the immediate gratification), but maybe there is something.
I can't think of a potential upside that you expose yourself to by watching TV (other than the immediate gratification), but maybe there is something.