^what gives you that assumption?
I own my own computer business and have worked alot with security.
As far as this hacking thing goes, 90% of hackers don't do it for malicious purposes. Hackers are hired by companies to help test and secure their system's vulerabilities, for the companie's protection. Or another great portion of people know it just for the fact of knowing and haven't done much with it.
To be a 'hacker' is much like what the other people said.. You must first know the ins and outs of computers. Learn everything you can. Also, computer security would be a huge thing to look into.
http://www.packetstormsecurity.org/ is a great source to keep up to date on system security and updates.
Essentially, in hacking, all what you are doing is looking for loopholes in a system and exploiting them.
A good rule of thumb too is that anyone who claims to be some elite hacker is most likely not.