Some of them do. Wage earners are not necessarily cash flow positive nor putting money toward hard assets. Plenty of people out there are renting, spending, and not saving. IIRC there's also a good bit of evidence to show that later generations are not saving nearly as much as older generations.
The price of renting is not unrelated to the price of buying. If homes are too expensive or unavailable for purchase, then the rental market will experience high demand, because people have to live somewhere. Buyers and renters may be cash negative for the same reason.
Again, this is why the inflation rates of housing vs. wages is crucial.