The real problem of bitcoin, however, isn't in this. The real problem of bitcoin is its huge waste of economic value. One tends to think that bitcoin is a zero-sum game, but it isn't: it is very very lossy. The value economically wasted by PoW is extracted from the system to go nowhere. In the long run, that's not sustainable.
This is from the book of the Bank for International Settlements and Co. Actually bitcoin is a perfect wealth creation machine (and not only for miners but for the whole society) that doesn't waste a single Wh.