[eosophos]

> It's lost work though, and the amount of work is governed only by the level of competition with other miners, rather than the amount of effort involved insome external task

It's the cost of securing the network. It's not lost. Fees and rewards pay the miners for the cost of their computing cycles, to provide a secure, very difficult (near impossible) to attack network.

[Nursie]

It's the cost of competing for block rewards, which incidentally secures the consensus, yes. It's the price of decentralisation.

And it's still not an external task, it's a facet of running the currency rather than work that is independently useful.

And it's still conjuring money out of nothing.