What you make in this game is dependent upon your play style. Personally I never tried to use it as a source of income, but I knew several people in game who were using it that way. My goal was having a little fun when I had free time and gaining skills and gear in the process. These can then be traded for real $. I always chose to keep my money in game for the most part and viewed it as a hobby. I'm a gambler by nature and pursued activities such as hunting and mining for the thrill of it. I could have taken my proceeds and put them into land deeds or some other stock like holdings and just sat there making a passive income, but that wasn't my style.
If one has the time and dedication needed to make an income from the game, it is surely possible.