He became famous when he was on the run from the FBI for a few years. This was one of my favorite stories: http://news.softpedia.com/news/Watch-Kevin-Mitnick-Explainin...
A lot of people don't know the history around him because it happened years ago. If you were following him at the time or if you've read his "ghost in the wires" book you'd see why he he's rightfully famous.
You're wrong. He's famous for a number of reasons, including a penchant for notoriety and the spotlight, but he was also a prolific pioneer of social engineering since before there was a term for it. He is/was amongst the best of the best of known social engineers.
I'd argue that social engineering is the most important skill for a hacker. And when he was "operational", he wasn't a "known", which leads me to...
> Being famous does not make you a good hacker, the best hackers will never be known.
This line may or may not be true, but it's tiring and obvious at this point.
I would be surprised if any pen testing group didn't have a 100% success rate. When you hire a pen tester or contract it out, the amount of information you get is absurd (but prioritized by severity).
Has a pen tester ever found a system that didn't have a vulnerability?