This kind of argument misses the forest for the trees. In any welfare system where we don't just say "screw 'em" to people who can't seem to support themselves

This kind of argument misses the forest for the trees. In any welfare system where we don't just say "screw 'em" to people who can't seem to support themselves enough to survive, there will be people who game the system. Now, I'd argue that those people almost always have the potential to be productive (and aren't productive because of motivational, situational, or basic economic reasons), but there is no benefits system we can introduce that will directly encourage these people to change. Yes, if we introduce basic income, by making things significantly better for everyone at the bottom we might slightly increase the number of people who don't contribute economically, and I agree that initially this feels like a moral problem that we might like to avoid. But in the grand scheme of things, I believe that a basic income will cause an increase in economic productivity (through increased access to education, less reliance on illicit activity, and removal of certain stressors that keep people locked in the cycle of poverty) to a MUCH larger demographic of people, vastly offsetting whatever inefficiencies are introduced by an increase in those who don't contribute to the economic system. Heck, even the reduction in bureaucratic expenditures might be enough to offset this cost. At the end of the day, any system will have a potential for introducing moral hazard, but I feel that any increase that might be introduced by basic income is vastly offset by the other economic benefits the system brings.