This has everything to do with our societies being powered by fossil fuels and nothing to do with bitcoin. High energy usage may be deemed wasteful, but if it was coming from solar power, it wouldn't be bad for the planet.
Life pro tip, if you don't want to be seen as a "crazy" person, slap on a pair of headphones and activate your phones voice recorder. You can pretend to be on a phone call, record your thoughts, and no-one will be any of the wiser.
Well maybe... it's certainly a different approach than being tracked, surveilled and served up personal ads.
Brave is using cryptocurrency as an alternative revenue model for content creators than advertisements, and in some ways it's much more of a "white mirror" kind of tech.
I think the key here to replicating the success is the deployment of deep learning effectively. But I would argue that deepmind's resource pool is immense, it's backed by Google. The resources of GPU's (and more advanced TPU's) are in abundance... not to mention the many brilliant PhD scientists who work there.