> A clean planet is a planet without civilization

That's not at all true, from either side.

To begin with, a planet can be "dirty" without any civilization. Most planets are. Look at Venus. Our own planet had already gone through 5 mass extinction events before we came up. The Great Oxigenation Event in particular does look like "pollution until planet death" without any civilization involved.

On the other side, it possible to have clean civilization - even one that cleans up more as it advances. You make it sound like it's an inherent problem - like civilization is "by definition" unclean. That is not at all the case. We have seen it is possible. What it isn't, is (as) profitable as simply not dealing with the externalities.

Civilization,Clean Planet,Maximal Profit: pick two.