We compared gold with Bitcoin many times here but it doesn't hurt to repeat it again because repetition is the mother of all learning.
They can even take gold from us but they can never take away out bitcoin if they don't have private key or backup phrase.
And here one of Satoshi Nakamoto forum posts comparing Gold with Bitcoin and his conclusion that not having Bitcoin would be net waste.
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.