Maybe that's why he was the first to find it. He was looking where nobody else had thought to look, and he just so happened to have the combination of knowledge and resources (edit: and talent) to find a flaw there.
He had found security glitches in his school's computers network as a kid. Also, he was hired by a security research firm while he was still an undergrad.
In addition to knowledge and resources, he also had the knack.
In college (1997? I was 17) I downloaded the source code of the unix client for back orifice. I read some of the source because I was interested in socket programming and reading Unix Network Programming. I compiled it, and deleted it without running it.
They were on edge because "god" from high school called to warn them about me.