"Perhaps it is the extreme hard labor that goes into mining that also justifies its value ?" - I think it is a fallacy to correlate cost with value. If someone burns up a bunch of money or does a lot of meaningless and useless work, he may benefit from the exercise, but he has not created value even though his cost was high and he worked a lot. Value comes from utility of the outcome. If nothing of use was produced, regardless of how large was expense or how much work was done, value was not created.
If same or better outcome can be obtained without the expense (mining), spending resources on it is fully wasteful. When there was no alternative to mining, it was justified, but not any longer, as much better and cheaper alternatives exist.