Why is "close" reading a valuable skill for college?

I close read all the time. every book that i have read, i close read. to me it is kind of hard not to, only because if i don't then i won't really understand it. then i won't be able to tell you what the book is about. i find it very hard to just skim through the book. especially if i read the back cover of the book and it catches my eye and becomes very interesting. if you just skim through the book the first time you read it, don't you feel like your missing out on alot of information?
When i read a book, i read it word for word and i try to make sense of everything i previously read. i enjoy reading alot. i read about 500 books over the past four years of my being in high school. when i read, it's like i am in my own world and space. when i am reading it is very hard to distract me. you could scream my name or do something right in front of me and i doubt if i would hear you or notice any of your movements. it will help in college because your professors will want you to get deep into the texts and this skill will definitely help you.