> The growing population of economically non-productive people requires a growing population of economically productive people to support them. At some point, you could take 100% of the output of the productive people and it would still not be enough to support retirees et al.

Economic growth is the result of productivity, which is the product of the number of people working, times their per-capita productivity. If each successive generation is more productive per capita than the last, then each generation can support successively more non-productive people.

But future generations won’t need to support as many non-productive people as we do now, because the Baby Boom will die off. In the U.S., the peak of non-productive populace is only the next decade or so.