That's a good question. For normal miners there's a similar question that's answered by a lack of unlimited capital. That wouldn't seem to apply here, since they're paying for the hardware themselves up-front and trying to recoup costs later. I can't figure out the answer here.

It doesn't make sense. There's no answer to figure out. If you have efficient miners, you either run them or sell them.

Then they have to pay for 100% of the power.

Minus the cost of marketing, distribution, product engineering, customer support, security engineering and lawyers (e.g. for dealing with the legal and security implications of managing customer wallets).

Additionally, I estimate that it's much more pragmatic for 21 to build a centralized ASIC farm at a location where power is relatively cheap with predictable costs as opposed to a geographically distributed ASIC network that will be subject to regional utility price variance.

Why bother with all that when you could literally just mint money at your leisure?