The way I see it, "return on investment" is never a thing with anything; yes, hardware eventually will fail after being used, fans will stop spinning, and hardware will burn; but that'll also happen if your computer is just sitting there idling cuss you didn't turn it off... or, if you're as unlucky as me, all my computers died after they were turned off, and they wont turn back on. This is meant as a method for people who don't have the ability to donate directly with real cash. (and lets face it, playing minecraft you're more likely to burn up your computer in an hour of game play on some mods / systems) The best argument I can make for "it costs me more money in electricity than I would get back in cash" look at it from a physics point of view: energy is never wasted; you're generating an excessive amount of heat that is now trapped in your room. oh hey, look at that, it's winter time and my heater is literally burning gas, or using electricity just to heat my room, why not off set my heater with my computer? the total amount of energy entering my room in the grand scheme of things would be the same, just some of that energy was used to run my computer that made some bit coins.