Because our society supported you when you were a energy/water guzzling sprog.

"Why should we others pay" is a worthy point, if the survival of the planet means anything, Of course. But, unfortunately, it turns out that half-assed parenting ends up costing society very dearly over time. By which I mean taxes and worse landing on your tab, anway. More jails, tons more depression and substance abuse, increasing illness and more. It's better to pay less, up front.

You'll surely want someone to pay for your retirement and healthcare, and provide the services you'll need.