Bitcoin is a PoW crypto; the heavy machinery required to mine it has made it a mining industry. What is it doing to Bitcoin?
Do miners dump BTC?
There is a misconception about Bitcoin miners that they dump Bitcoin, but this is not true, because mining Bitcoin and selling it is the natural process of Bitcoin. The BTC maximalists, like Michael Sellers, buy their bitcoin from miners, so it is actually fresh transactions and not dumping the BTC.
Why don't miners HODL?
Bitcoin mining companies work for their own profit and employment, so by selling the results (Bitcoins) obtained from mining, they meet their various expenses, and pay salaries to their employees. Even if they do not sell Bitcoin, they will have to pay for all expenses in Bitcoin. Therefore, HODL cannot be their objective.
This is also necessary for the market
The value of an item depends on the market. If people only HODL, then Bitcoin's circulation in the market may stop, and the value of the immovable object will also not be maintained. Mining companies keep BTC trading active by continuously mining Bitcoins and bringing newly-minted BTC to the market.