Every now and again read something difficult; something that makes you think and leaves you confused. You'll learn more in the long run. A great place start, if you happen to be interested in math, is Terence Tao's blog, and a number of the blogs he links to. (At the least, I find it challenging; the blog is over at http://terrytao.wordpress.com/ .)
Tao's blog is excellent, but how does one acquire the background necessary to understand his mathematical posts? By rolling up one's sleeves and doing hard work, most of which is likely done away from the internet. And this is the kind of thing that spending a lot of time on the internet makes it harder to do. That's my experience, anyway, as well as my observation of others'.
I am going to follow your advice, disconnect, and try to really understand some books.
I love the internet, not least because of the ease with which I can obtain information that used to take hours in the library. But obtaining specific facts is not the same thing as learning or thinking.
From observing myself and others, I believe that something is wrong. I'm getting way more brain stimulation from the internet than I used to without it, but in terms of things that matter to me in the long run -- growth and learning -- it is of poor quality. I remember the quality of a life spent with books, and this is definitely not it. I feel like I'm experiencing my own atrophy, and it dismays me. Sometimes I think that one of these days I should post a list of books to HN and promise not to come back until I've read them.
So no, consuming information from the internet is in practice nothing like getting an education in the humanities, for anyone whose brain is wired like mine and those of people I know.
Books are food, the internet is a drug.