In World of Warcraft everyone wants a faster mount or better equipment. These things require that you have large sums of gold and there are many players who will resort to buying virtual currency with real world money. I do not know about you but I think that those who resort to this have must have more money than brains.
I work hard for the cash I earn in real life and am refuse to shell it out for virtual currency, especially since earning gold in World of Warcraft is so easy.
Human beings are lazy by nature and that is a point that you can take advantage of both in the real world and in World of Warcraft. In real life people would much rather pay someone else do things for them than do the work themselves. The same mentality holds true in the World of Warcraft universe.
There are thousands of crafts people on every server and the vast majority of them would rather pay for the materials that they need at the auction house than to mount up and go out and gather them for themselves.
If you really want to rake in mountains of gold in World of Warcraft all you need to do is turn your character into a gathering machine. Pick professions that are gathering professions such as mining, skinning, or herbalism. Mine, skin, or pick herbs as you are adventuring then put them on the auction house and you will never be out of gold.