If I understand correctly, the computational expense of Bitcoin mining is increased periodically to track any improvements in hardware or software. The value o

If I understand correctly, the computational expense of Bitcoin mining is increased periodically to track any improvements in hardware or software. The value of Bitcoin is thus supposed to be tied to some underlying measure of value. We used to have gold-backed currency. Then we went to fiat currency. It seems like with Bitcoin we are going to coal-backed currency. If nuclear fusion became a thing and energy prices went to near zero, would Bitcoin expand to the point that it was using 99.9% of all electricity? Personally I think this is a ghastly waste of energy.