Why? Supply and demand. If there is demand then it's fine. If there isn't any thats ok as well.
Its climate arson.
Aren't there oil ETFs or other types of ETFs that have a much higher negative impact on the environment?
Any sort of currency seems to bring out the worst, maybe currencies in general is the problem?
Bitcoin mining incentivizes finding the cheapest source of energy, accelerating things like the adoption of solar or using flared gas to power data centers instead of burning it into the atmosphere. Research deeper!
There's sizeable market failure in the form of externalities, in this case emissions tied to its energy usage.