A lecture hall should be like a church-a little too dark, much too cold, and uncomfortably silent. You should feel guilty opening your water bottle, because all 200 people in the room can hear it.
So when I'm trying to pay attention, the last thing you should be doing is carrying on a conversation about your last weekend party or anything else.
During the past school term, I've had enough. One of my biggest complaints of large class sizes is the tendency for three to five friends to sit together and loudly whisper each others' ears off for an hour and 15 minutes straight. My stupid monkey brain can't help but focus on your conversation about the difference between ash blonde and light blonde colored hair that look exactly the same.
To me, it just feels like a waste. You're actively wasting money, and missing vital information. We (and the government) pay quite a lot for our education, but you are here to ignore someone significantly more experienced than us, in classes we picked, for hours every week.
I know major requirements can be boring, but this is still an education. It requires two-way effort. Most of students here have at least one goal in common: success. Not every checkpoint on that path is going to be filled with joy. Sit down, shut up, and force yourself to listen to your professor. Society tells us it will eventually pay off.
Or maybe it won't because you don't want to.
I actually don't care if you decide to pay little or no attention to the lecture itself, so long as you're not being disturbing.
For those willing to try, in 20 years when you finally pay off your debt with your fairly secure white-collar job, you'll look back and be happy that you went through the lectures.