The idea of urban renewal is getting people to move back from the suburbs into core cities or satellite cities. Your contention was that this is ridiculous, because for "99% of the population" their urban living options are places like Camden, not NYC or SF. My point is that 25% of the population lives in metro areas where moving to the core city or a satellite city would not mean moving to a place anything like Camden. This is particularly true for places like New York or Chicago (combined, almost 10% of the whole U.S. population), where you can live in a little satellite town with a walkable, urban, downtown area, and commute to work in the core city on METRA/Metro North/LIRR/NJT.

Re: school statistics. Chicago also has 90% low-income in the school district, but there are tons of middle class people in the city. A lot of the gap is filled by parochial schools. For example, Chicago has ~400,000 school aged kids enrolled in CPS, 87% of which are low-income. But it has ~615,000 school-aged kids. There are 30,000 kids enrolled in Catholic schools alone.