I've read a few of those and it's extreme copium. For example, many of them point out that the Bitcoin network can use renewable energy. Yeah sure, except for one problem: So can everything else. If Bitcoin uses some amount of renewable energy, that's less renewable energy to go around. This basically only matters in places that are powered entirely by renewables...

The most ridiculous point I've seen by far is the idea that actually, energy is not "wasted", because it's actually generating heat. It is true that computers are 100% efficient space heaters, but that's not the point.

The point is that if you scale the Bitcoin network up, it would put tremendous strain on the energy grid. That's not FUD at all!