[paulgb]

I think you nailed it, although I don't think miners even need to fall for a fallacy for your argument to work: some major miners have made big capital expenditures (efficient hardware, cooling, etc.) to keep variable costs low over the long term. Even if the price drop means they'll never mine themselves out of debt, it could still be the rational thing to do for them to keep the machines on, as long as their reduced variable cost is still below than the market price.