The figure’s misleading, because mining (these days) is done with specialised hardware: ASICs, chips dedicated to calculating SHA256 hashes (or whatever algorithm your favourite coin uses), which can calculate those approx. times times faster (per second per $) than a general-purpose CPU—but can’t do anything else.
So that implication may well be true in the sense that if all the worlds computers turned to mining bitcoin, the total mining capacity would only be increased by a couple percent over what it is at the moment (due to general-purpose computers being so inefficient at specific tasks compared to dedicated hardware). But false in the sense that very little of the world’s general-purpose compute capacity is tied up mining cryptocurrency.
I also commit to donating £5k to lightcone if and only you can get UK gift-aid donation set up by the end of March.