There are a number of illicit ways to earn money using a computer...someone who is, by all definition, a hacker...well they can do a number of things on both sides of the law.
On the "illegal" side, you'll see identity theft as the number one way. They will get your personal information and open credit cards in your name, that kind of thing. Another way is to straight up scam people. This is done through things like rogue antivirus which hijacks the machine and promises to release it when you pay up some money.
Some hackers do the dream job of freelancing for people who need something hacked. They are the mercenaries of the internet, and people may hire them to take down a site, or to get a site back from the grips of another hacker. This is "gray hat" realm...where things are not necessarily legal, but they are not quite as immoral as the straight up black hat realm of hackers.
The white hats are the consultants. These hackers will teach a company how to secure a network the RIGHT way. Most people seem to think if you take a few classes on security, you're all set...you honestly need someone who knows how to hack something if you plan on getting it secured.
In any event, if you want to make money as a hacker, you'd better be damn good and have some connections. There is no room for the hobby hacker, or the person who visited a couple tutorial sites and thinks they are a hacker.
If you've never pointed out a new kind of vulnerability or at least a variant of an old one, you won't be cashing in on your '1337 ski11z".