According to the Cambridge Bitcoin Electricity Consumption Index (CBECI), the estimated annual electricity consumption of the Bitcoin network is around 114.67 terawatt-hours (TWh) as of September 2021. This represents approximately 0.5% of the global electricity consumption.

中本聪在2010的看法如下，那时候比特币挖矿用的电力还很少，用的是一般的电脑，还没有开始用GPU挖矿， 更不用说矿场和矿池。https://bitcointalk.org/index.php?topic=721.msg8114#msg8114

It's the same situation as gold and gold mining. The marginal cost of gold mining tends to stay near the price of gold. Gold mining is a waste, but that waste is far less than the utility of having gold available as a medium of exchange.

I think the case will be the same for Bitcoin. The utility of the exchanges made possible by Bitcoin will far exceed the cost of electricity used. Therefore, not having Bitcoin would be the net waste.