[fauigerzigerk]

I agree that it does look disproportionate. But my understanding (I'm by no means an expert) is that it could theoretically become less disproportionate as more transactions are being processed.

Proof of work is not a per transaction cost. It's a per block cost that doesn't depend on the number of transactions per block or the size of the block.

But still, the way the incentives are structured in this whole game seems somewhat perverse. Otherwise we would never have gotten to a point where bitcoin mining has a country sized energy profile.

[stordoff]

It's not a per transaction cost, but as I understand it they are closely related and there is no upper bound on it. As the number of transactions per block and the value of the currency increases, it becomes more profitable to mine, thus it makes more economic sense to invent more power into it.