I think for nearly every student who doesn’t really have to study but gets good grades, at some point they hit the wall and the party ends. I have a son who discovered this as a freshman in high school. He never had to do much and always got very good grades. Sadly, because of this he didn’t learn to study or manage his time. He was a bit shell shocked as you are. Now he is a sophomore and he’s still trying to figure this out. For you, your party ended when you hit college. Yes, you have to study a lot and use all the resources available to you.
As far as the social adjustment. Keep trying. It’s hard and I think harder than ever for your generation with the reliance on technology to fill time and socialize but if you keep at it, your social group will come along. If you have that the work will be less annoying to you. Good luck!