I am enjoying the subtlety of your Darwinian argument.
One friend of mine suggests that we need to make adult play centers that have pitfalls, like dead drops, to keep people fit and alert. The kicker is that they would be placed in such a way that it would be necessary to traverse them to get to essentials like the DMV, liquor store, etc.
But I guess the big question is whether you think these people on drugs will create a massive amount of collateral damage or not on their way to thin themselves out? I imagine cars crashing through walls, people passing out with their stoves on and burning down their apartments, strung-out people electrocuting themselves, that kind of thing.
Less losers = less problems.