Resources for doing anything are limited (by will, as well as for other reasons). It necessarily follows that putting resources into space exploration reduces those available for "fixing the rot" (although sure, not necessarily by equal amounts).

If fixing the rot were genuinely an extinction-level imperative, I'd say we should devote zero resources to space exploration. However, I don't think there's an extinction-level event or period coming at any point in the foreseeable future, so I don't think we have to be that dogmatic about it. Even so, I'd far rather see us defer all fossil-fueled adventures until (if!) we get this place into better shape.