1. Employment: Skilled ethical hackers can earn good salary by doing part time or full time job at government and non government offices.
2. Self Employment: Ethical hackers can create own website and share their knowledge to get maximum income. You know how a website makes money. It's by different ways like contextual ads, affiliation, etc.
3. Free Service: Ethical Hackers can find out the security vulnerabilities in other sites and inform them through email and other medias. In this way they may get reward by the website owners. The popular site like Facebook gives large amount of money for this type of service.
Obviously, there are many other ways to earn through ethical hacking. If you have got any other ways like mentioned above, you can share your ideas through the comment form below.
Discovered by +Don Prince