The absolute majority of things in life that are valuable do not come easily. Depending on the specific way(s) you are trying to earn money online, it may require consistent effort, problem solving, talent, and creativity among other things as well. Just as with any other money making effort.
I would definitely keep at it if I were you. If you enjoy writing you can get paid per project if you would like by visiting websites such as ELance.com, Textbroker.com, and ODesk.com. Also, you may have a great idea in your head that could help make a process easier or you could just have a great product idea that people would pay to buy. Perhaps you have a skill that others would pay for besides writing.
I say all this to say to make clear to you that if you want to earn money online, you can. It takes effort and thinking outside the box. You have to have more of an entrepreneurial mindset and good work ethics to build an income online. Take for instance here at hubpages. The writers earning the most did not get there overnight. For many, they have been very active for a minimum of two years.
By no means would I say it's easy to make money online or claim that I am an expert however I do know a couple of people that have been able to make very comfortable and affluent live completely online. They are goal oriented and self motivated people who prefer working for themselves rather than others. If any of these things ring true as descriptions of you, keep at it. Best of luck.