People like come up with "Bitcoin uses more electricity than <small country>!" as a shock headline, but that's just statistical chicanery. A very small percentage multiplied by the whole world is a large absolute number. It's like saying "the global paper industry uses more electricity than all of Australia!" People think of Australia as being big, but as a percentage of the whole world, not that big.

The primary advantage is that cryptocurrency mining is highly price sensitive, so if you have something like wind turbines that produce more at night even though there is more demand during the day, it can be profitable to only mine cryptocurrency at night. Which increases the revenue for the wind farm and makes it more profitable, which means we can have more wind farms and fewer coal power plants. But only by like a half a percent of the power grid, because that's how much is going into Bitcoin.