How do you make money online? Why is it so hard?

I've been trying to make money online and been unsuccessful. I've been good at solving problems when I worked for others. All my previous employers ask me to re-join them at sometime, however as I want to be independent I try to make money online and I've failed many times. I wish there was a place where you could just log in and solve database, coding, scalability issues.

What's your success story in making money online ? And I'm talking the 500-1000$ jobs.