Probably should google this a bit more before posting, sorry... ;-) But the world is /actually/ using resources (time, parts, and electricity) of "mining" a (unbacked, but I guess most are ;o) crypto currency?!? No useful work is actually done (?); the machines are just calculating random stuff made sufficiently difficult to match the hardware of today? I hope I'm missing something here - but I say use the hardware/electricity for fun or work and leave the waste of resources to....hm... can't really think of a "purpose" that not either useful or fun... [2 degrees target long gone! And US out of Paris?!]