This is totally true and it should be engraved in stone, since Bitcoin evangelists seem so much in denial of that.
And even worse than this, PoW mining has also resulted to be totally unsustainable from an ecological point of view. Not only the waste of resources which heavy mining implies is basically nonsense, but it even could contribute to jeopardize human life on earth by accelerating global warming until it eventually spins out of control.
And that's not only me who is saying it. Please enjoy this article on the theme on prestigious magazine Nature:

https://www.nature.com/articles/s41558-018-0321-8.epdf

Byteball is much more likely than Bitcoin to spare human life on earth from extinction.
Not that this is necessarily auspicable, of course...