It depends on how much you value your time. Lectures usually are shorter than 2 hours per week. (There are some that have longer videos, but I think more than 2 hours is suboptimal.) I know that before courses I was wasting this time on hacker news or reddit, so I don't value my time that much. On the other hand I do now, and that's because I need to watch the lectures and do the home work. And really these lectures perform the same role in the learning process as the real lectures. You could graduate from university only with text books, but you might not get some insight that lecturers have.
My 0.02 chf.