Bitcoin has the culture of hodling* so I doubt how much of the pre-existing coins go into the market. So mostly the local currency (yuan/etc) would go to cover the mining costs and salaries of employees and owners. Don't know the impact of closing down of exchanges in China some time back.

* - holding but culturally called hodling, perhaps some Grame of Thrones reference(?)...Satoshi did not move their coins and that carries on. So far it has been very resilient. Exchanges hacked and it carried on. But fear remains of some black swan events e.g. Suddenly Satoshi coins on the market etc.