Isn't it important to consider how much electricity is used by alternative forms of status-seeking? This is hard to quantify, but the counterfactual world where there is no status-seeking, or even where there is less status-seeking, is sort of hard to imagine.

I see it more as a fake-altruism-signaling game - eliminate the harmful signal (Folding@home), and the activities aren't 100% displaced into other activities, more or less harmful (I don't think the demand is inelastic); to put it another way, https://www.xkcd.com/871/

By the way is this number available in QALYs?

I didn't see QALYs mentioned. My general understanding is that air pollution disproportionately hurts the old, so the QALY loss is not so bad as it could be, but then, the comparison is to interventions in Africa focused on kids, who have many more potential QALYs than old Westerners... so I suspect on net it strengthens the case against Folding@home.