If they have money to sit around and get high, then it means they have a means of income and they are contributing to the economy. And the fear of dying alone is not a good contributing altruism for having your own children. I'm not saying it's the only drive behind people having kids, but it shouldn't be pretended that it is not selfish.
If you were over at their house at the time they were doing it, it doesn't mean that that's the chief thing they put meaning into, nor the chief thing they conduct, with their life.
That is if you barged in and saw me passing fecal matter on a toilet, are you going to assume that I sit on the toilet and shit my life away 24/7?
And in the very least, they're married.