I don't see how the calculations support that.

For example if we use your worse case scenarios of an entity (such as Suchflex) that had its own datacenter in a 20 cent kwh region and the crowdsourced homecomputers in a 9 cent kwh region, that's a difference of 11 cents.

If we round up the energy usage to 600 watts (pc + GPU), that 11 cents is an annual difference of ~$578. However, for Suchflex to even run computations at all on their own hardware -- whether its 20 or 9 cents -- they have to spend capex of ~$1500 of motherboard+cpu+gpu. That's the $1500 the homeowner already spent for his own purposes. Therefore, Suchflex can redirect $1500 to pay commissions/awards/etc towards pure computations instead of buying their own depreciating hardware (which includes buying/renting the physical datacenters to hold it all).

It seems like the homeowner's hardware is a very significant part of the arbitrage/monetization equation. Yes, there is also potential arbitrage in regional differences of electricity rates. However, the greater arbitrage (at least the first 3 years) is the unused time on residential pc that would have been wasted. That "unused time" arises from computer hardware that was already purchased for other purposes than Suchflex.