At first, some people playing online games started to play that game and sold their equipment to others. Generally, an account costs thousands a month. If a studio runs many accounts at the same time, it will cost tens of thousands or even hundreds of thousands a month.
Now there are only various online businesses, such as product promotion and water army.
The most normal and formal is the online store. There may be only one person selling things, but many people need to do all kinds of marketing promotion on the internet. ,
In short, anyone who can make money through internet plus can open a studio.