It's a price ceiling, not a floor. If prices go up high enough, it's worth turning on EC2 instances and paying for them with the mined cryptocurrency until prices fall. There's some wiggle room above the break-even point, since there is some delay between turning on miners receiving USD, and the miner has to eat that risk.

Ah, yes, that makes sense, thank you!

not if you have a free-fall dump going on. This happens when investors lose hope in the long term future