Captain Internet's pride comes not from knowing facts, or even providing useful information, but from knowing something that someone didn't know and proving that they knew it first.
While Captain Internet is a relatively new phenomenon, they are direct descendants of Captain Encyclopedia, who dominated post-conversation follow-up throughout most of the 20th century. Their rise has in part been aided by the posting site Reddit, since posts are time-stamped, allowing Captain Internet to prove that they were first to learn something.
friend: "have you seen this Gangnam Style video?
Captain Internet: "yes, that blew up last year. I saw it first on Youtube when it only had 100,000 views."
friend: email "look at these security images of cougars found stalking around a house in town"
Captain Internet: "I saw that on Reddit 5 days ago, here's the <link>"
friend: ".. and that's why carbon dioxide needs to be expelled from your lungs or it will become toxic.."
Captain Internet: "oh, that reminds me of this interesting lake somewhere that slowly collect carbon dioxide in it somehow.. I forget it's name"
4 days later
Captain Internet: email "here's the link for Lake Nyos, a lake in Cameroon that absorbs carbon dioxide from a volcanic vent underneath it, here's <link>"
friend: "thanks Captain Internet"
Captain Internet: "is that a real thing?
friend: "yes, I just made it up"
Captain Internet: "that's actually already on Urban Dictionary, here's the <link>"