Of course the welfare system is sustainable. Welfare is sustainable. Until you have more people on the roles than are working. Then .. not so much. I would

Of course the welfare system is sustainable. Welfare is sustainable. Until you have more people on the roles than are working. Then .. not so much. I would say that welfare is sustainable at the time it was enacted, and for that time period. A good example might be US Social Security. At the time, relatively few people lived more than a few years past retirement age. This is sustainable. Time passes. People live a lot longer, there are more people drawing on the system. There are more benefits _in_ the system than originally imagined: old people vote and they vote (as a block) for pols who will give them stuff. And then more stuff. I'm simplifying of course but .. welfare is not sustainable because people want more stuff and initial conditions change.