Computers as a whole burn the energy of many small industrialized nations. Is that to say computers shouldn't be used? Or is it simply a statement of how widely used computers are?

you need to take the cost/benefit. Computers may use a lot of energy but they're essentially the nervous system of collective humanity now - they're eminently useful. Cryptocurrencies on the other hand - their primary utility is taking person A's money and giving it to person B without producing any beneficial side effects.

Nuclear energy vs nuclear bombs? How you use it makes a difference?