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No one initially. Just because miners are minting 1800BTC per day on average, it doesn't mean they will be sold automatically - miners are known to keep holding on to their coins after minting. If they end up cashing out a certain part of their mintings, they do that gradually to not drive the price down too much, because at the end of the day, they don't want to ruin their own game.
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This is definitely true. Especially, because holding on to the BTC for some time has almost always been the most profitable
play in the last 8 years. Most miners probably need to sell at least a part of the mining rewards in order to pay for
electricity, payroll, hardware and taxes. But most miners have been around for some time and therefore
have accumulated a "warchest", which enables them to hold on to their coins for longer and by this
increase their profits.
Besides, most mining pool operators are big believers in the technology of Bitcoin as well, which makes
it even more likely that they are long-term holders.