There is nothing wrong with using energy. Do you live in a dark cave and eat raw vegetables?
Users of electricity are not polluting. The polluters are the generators of electricity. If electricity generators switched to solar or wind, you would have nothing to complain about.
OP's got a point though, the power usage is freakishly high but OP did not account for energy alternatives. I do not necessarily agree with some of his points but we need to address that energy consumption matter at hand. The usage of renewable sources is still low around the globe and I think the community can do something to help in the progression even if it is small contribution.
How much energy usage is too much? What criteria do you use to determine how much is too much?
The energy from the sun is a hard cap (assuming no nuclear, fossil fuel, tidal, or geothermal generation) so it makes sense to put it in those terms. The earth receives 174000000000 MW of energy from the sun, and Bitcoin uses about 9000 MW, or about 0.0000051%. In those terms, energy usage by Bitcoin is a long way from being a problem.