> Why bother digging up a carbon laden energy source from the depths of a gravity laden planet instead of using solar energy or wind or any other energy source that is less harmful?

Well at least one reason might be that you're currently unable to use those latter forms of energy as well as you can the former.

Anyway, using the way we act as a comparison for how these other civilizations might act doesn't make sense to me - we're nowhere even remotely close to being a threat to other civilizations. By the time a civilization reaches the point where they can travel between stars, I do suspect they'll be using renewables pretty dang heavily