How Much Space Does A Person Really Need?

A person doesn't just live in their personal/private space -- but lives in the public/community spaces also -- which could include a gym/health club, parks and gardens, public library, Starbucks, etc., which the urban areas are renowned for.

Her apartment, is essentially only her bedroom, kitchen and private bathroom -- which should come as a premium to a shared living room, shared kitchen and shared bathroom, that many larger living units have. 

If all places were priced the same, then the congested areas would be even more crowded -- while desolate rural areas would go begging.  Even the homeless realize that -- and so they congregate in the cities rather than populate the rural areas.

So price plays the important function of regulating the traffic to manageable flows.  Those guys on the space shuttle and submarines are lucky if they have 100 sq ft each -- for extended periods of time, requiring high performance functioning.  And when space is extremely valuable, you have high maintenance costs for heating and ensuring livability (air quality) -- under those conditions, for those who choose to remain in those habitats -- and many others, rightly move on to greener (more spacious) pastures.

But even when space is plentiful and cheap, one still has to maintain it -- as most homeowners with yards know too well, and if one doesn't want that yardwork to be their favorite pastime by default, then they forgo that responsibility and liability.  It increasingly makes sense for a lot of the retiring seniors particularly -- who should be downsizing (divesting their lifetime hoards), and eliminating stairs and other hazards to their mobility, as well as reducing their risks of injury (home repairs).

Many just sit in their wheel chairs all day -- anyway, which is 5 sq ft.  A bed is usually 20 sq ft, but some people even sleep in their wheelchair/beds.  One can store every possession they've ever owned and need to their one computer and cell phone -- on themselves, so they are virtually living, with all the things they need to access -- wherever they are -- in the total environment, of which they need just enough versatile and efficient personal space that is a mark of their organizational and functional intelligence.