Now I take my phone even to the bathroom, and as soon as I get home and lie down, I start scrolling through videos and social media, absorbing tons of fragmented information until I feel dizzy. Why can’t I stop doing something that I know is harmful and doesn’t even make me feel happy?
From your post op it seem your deeply addicted to the phone and to stop it you need find others means of this that keeps you busy as the phone where your attention can be channel to if not it's hard to stop so easily. Another alternative is to avoid charging the phone so as to reduce your attention to it you can intentionally ignore charging the phone or make use of button phone where you can't have access to video and those things that take you much time and focus on call and receiving of calls through button phone that's my opinion it will help you.
Not a bad option, but people with such an addiction find it very difficult to concentrate on anything else. Personally, I think the best way is to give your phone to someone close without the possibility of returning it for a certain period