Bitcoin gets less and less energy efficient over time given that it gets more scarce the more that are mined.

Sure. Original Bitcoin.

But there are a thousand competing shitcoins that are all reinventing the cryptocurrency idea, and every new one reinvents the efficiency of early mining and lets people forget that it all grinds to a halt above a certain soft ceiling. Miners can keep doing this as long as they can get a new set of suckers to sign on to the next "improved" math model. Meanwhile, the astronomically high per-unit price of the original gives people the impression that the sky will forever be the limit.

It's such a crazy system.