Fame requires that you are topical. That's what separates fame from skill or talent. Paris Hilton, for example, is quite famous even though I would say someone like Susan Surandon is much more talented.

Chuck Norris stopped being talked about years ago. He was no longer topical, no longer “relevant.”

This Internet meme made people remember him again, and suddenly he became much more topical — more “relevant.” He owes the Internet (in a general sense) for providing the distribution channel that spread this meme.

More than that, however, he owes his fans a little patience considering this entire thing was just supposed to be a joke, not an attack on Chuck Norris' character.