Energy spent with a purpose is not waste. This is the case if you spend energy to build a car, and also when spending energy to calculate a proof that prevents altering historic information.

In the former case, consumers pay car manufacturers to spend energy to produce cars, in the latter case bitcoin buyers pay miners to spend energy to secure the blockchain. In both cases, if the end-user of the (virtual) good ceases their activity — consumers buying cars/people buying bitcoins — the good in question will automatically stop being produced (miners don’t burn off energy to produce bitcoins if they can’t sell them for a profit).

In this way, Bitcoin works just as any other consumer good: the (bitcoin) buyers finance the activities of the producers (Bitcoin miners) in order to produce a useful tool (electronic cash).

It provides me value so its not a waste.