Let's entertain this argument for a moment.
1) You buy mining gear with fiat that is not needed elsewhere. As this fiat was available there is no need to dump coins in a bear market. Wait for next ATH. Net market pressure: Up.
2) You take a loan, mine and sell regularly to pay the loan back. You do not sell 100% of them regardless of price because you did your calculations beforehand. The coins you do not sell are now unavailable to the rest of the market, increasing scarcity and therefore price. Net market pressure: Up.
3) You are bad at math and mine at a loss. You either turn off your miner or bleed money until you end up in the gutter. Net market pressure: Down, but temporarily.
Not being a miner myself, it's possible I missed something. But so far, it looks like sustainable mining is good for the price.
I'm actually looking to be proven wrong here. But with logic and numbers, not trolling. Thanks in advance.
I like your first point, fiat analogy is a spot on.