You're wasting energy for posting comments too. If we think a way like this, we can't no anything.
Bitcoin was ALWAYS going to be inefficient. It was assumed that hardware would scale to keep up with demand, but that hasn't proven true in the advent of ad hoc mining pools.
No, it was designed to stay at "one block every ten minutes" regardless of the hardware added or overall hashrate of the system. Which is why you hear a lot of people arguing over block size and block compression: you always have one block every ten minutes, how many transactions can we squeeze into that block?
The only thing that adding more hashrate does is waste more power, since the network will adjust.
Each post uses as little electricity as is feasible. Efficiency improvements lower the amount of electricity used. Reducing the use 90% would mean 90% fewer posts and ruin the posting experience.
Bitcoin doesn't try to minimize electrical use. Efficiency improvements increase the amount used. Reducing the use 90% would lower the transaction rate 0% and ruin nothing, but we can't do that because it's set up as a competition.