Nothing could be further from the truth. Now this may sound like a rather silly question, but it bears asking. The most obvious clue would be that they have been caught and convicted of a computer related crime. Kevin Mitnick, a very famous hacker, was caught several times, and spent time in jail.
Most hackers possess very little actual skill.
They simply follow in the footsteps of others. It is very easy to download precompiled exploit scripts from sites such as rootshell and then use them to break into systems. Even assuming for a moment that this person has any advanced computer security skills related to breaking into networks, this does not mean they have the skills needed to secure networks. It is one thing to find a weakness and exploit it, but it is an entirely different matter to fix it properly. Securing a network takes a lot more then plugging a few technical holes.