Humans around the world are consuming food, heating/cooling themselves, all in the service of some gamified activity. Some of these activities are as useless as mining Bitcoin. Yes, these activities aren't burning through energy, but people are burning through energy, with the sole focus of doing the activity.
Any justification for these activities can most definitely be used to justify people wasting energy on mining Bitcoin.
This reasoning has no bearing on whether or not bitcoin is a waste of energy or whether its energy use is justified. It is akin to saying, "Sure, I burn ten tons of coal a day to power my iPhone, but someone else burns twenty tons a day to do the same thing. Therefore, I'm not being wasteful." This logic doesn't cut it.
I was making an argument that deciding what is a valuable human activity does not include wastefulness at all. (OP was implying that someone from the future will value these mining efforts in a regretful way)
People are having fun earning money by burning gas and mining Bitcoin. There are so many other equivalent activities that do not receive any uproar but are even more wasteful.
For example, eating meat is insanely wasteful. Yet you will find people defending it.
Wasting energy is the thing we do for various reasons. The underlying "regret" that someone from the future should have due to it not being productive or useful is completely irrelevant. We rarely do things because they are energy efficient.
I'm just laughing at the inconsistency. If people were really consistent in their views of (un)justified waste, I just don't see the same uproar to those other magnitudes more wasteful things (like eating meat, spending a life playing video games etc.).
It's like being mad about one of the fastest functions in your code when there's many others to optimized.
I also do not want to talk about the philosophical side to taking a life of an ant (delve into what waste is justified or not, and which degrees of dopamine response would justify it).