Furthermore, the only people who have control over the energy consumption of the mining network are the bitcoin miners. They have extreme amounts of attention directed at energy efficiency. Miners are thinking about electricity costs very often as it's the base cost of operation.

There have been many step changes in efficiency. On a per-hash basis (and security of the network is directly proportional to number/difficulty of hashes) I'd estimate the efficiency of bitcoin mining has increased a million- or even billion-fold in the last decade.

Miners are making their decisions based on the price, which is set by the market: the amorphous sentiment of a crowd of millions of strangers. The price of bitcoin is directly proportional to the rational amount of energy miners should expend mining it.

There is no "make it more efficient": it's already being pushed to be extremely efficient all the time. That you believe bitcoin is not efficient enough is irrelevant and probably unfounded. The market likes it, and you're yelling at the market about efficiency, but the market already decided what the rational amount of electricity to expend securing the network and settling transactions based on the current price.

The only reason you think it's using "too much" energy is because you don't understand the security value of chained hashing.