This was also included in the aforementioned article as another way to earn money playing video games.
I don’t recommend you do it, but it’s fascinating to learn about.
As per Wikipedia:
Gold farming is the practice of playing a massively multiplayer online game (MMO) to acquire in-game currency later selling it for real-world money.
Similar but different is Power Leveling:
Power-leveling is using the help of another, stronger player to level a character more quickly than is possible alone.
Sounds kinda cool: people who are money-rich and time-poor will pay you to earn them accolades in video games 🏆
The downside is that the work is mostly boring and the pay incredibly low 😢
According to a 2016 article on Cracked.com, Chinese prisoners are required to gold mine as part of their sentence, and even free folk who do this kind of thing seem to earn about $6/hour at best.
Oh, and many game developers forbid gold farming, so it’s a bit shady in that respect, too.