> Just what is an acceptable amount of energy to secure potentially all of the wealth in the world? As little as necessary. While Bitcoin incentivize to spend

> Just what is an acceptable amount of energy to secure potentially all of the wealth in the world? As little as necessary. While Bitcoin incentivize to spend as much energy as possible, up to the (partially arbitrarily specified) mining reward as financial cap. Also it is very dishonest to compare potential address space to actually used address space. You could easily extend the number of digits of current bank account without really increasing energy consumption. If you'd actually start to use those address spaces Bitcoin again would scale a lot worse, since nodes would actually have to spend computing power to process all wallets. Hell the current bitcoin blockchain size already makes running a node not worth it for me, thus we might should not promote its scalability. Though this has less to do with proof of work. By the way i wonder how different POW algorithms and chains with similar ones will be able to coexist in the long term without weakening its POW.