No. "the pie" is total productivity, and "the pie eaters" is total consumption. Every human is both producer and consumer of this pie. The problem is not over/u

No. "the pie" is total productivity, and "the pie eaters" is total consumption. Every human is both producer and consumer of this pie. The problem is not over/underpopulation, but the distribution of producers and consumers. Young people are more productive than old people, and that's why declining birth rates (and longer lifespans in retirement) are a problem. The scale is tipping to having more consumers than producers.