I see how one can be more apt to care if they have children, but you stated it as a definitive general rule. I personally don't have kids at this point, but I care very much about the future world. I could be an anomaly, but I don't think it's nearly as black and white as you originally stated.
This kind of reminds me of the argument that since black athletes are millionaires, they shouldn't talk about oppression. You don't have to experience something to say it sucks. You don't have to have a blood investment in the future to realize that it's better if we look forward and plan ahead.