A correction - bitcoin is not anonymous enough to enable any of the use cases you mentioned. But that misses the points - tools can't be blamed for secondary use cases - do you blame physical dollars for enabling child porn?
As far as our carbon budget, how we choose to create energy and how much energy something uses are unrelated concepts. If people pay a proper price for energy that reflects its scarcity and externalities, then there is no problem. In a world where we use 100% renewable energy sources, would you complain about bitcoin mining? In any case, one could argue that the amount of energy required to secure the bitcoin network is a drop in the bucket compared to the amount of energy that (for example) the USA uses to secure the value of the dollar. If we then factor in the pretty obvious benefits of a decentralized currency, it seems like a great idea if the downsides can be properly addressed.
As far as our carbon budget, how we choose to create energy and how much energy something uses are unrelated concepts. If people pay a proper price for energy that reflects its scarcity and externalities, then there is no problem. In a world where we use 100% renewable energy sources, would you complain about bitcoin mining? In any case, one could argue that the amount of energy required to secure the bitcoin network is a drop in the bucket compared to the amount of energy that (for example) the USA uses to secure the value of the dollar. If we then factor in the pretty obvious benefits of a decentralized currency, it seems like a great idea if the downsides can be properly addressed.