When I first moved to the SF Bay area, I was surprised by the amount of visible homelessness and by the number of service economy workers who drove nearly two hours to and from work.
I also had my first experiences with the "campuses" of major technology companies, where money was made hand-over-fist. I think the recent widening income gap is a natural consequence of the technology we have invented. A relatively small number of people are able to generate a relatively large amount of profit; this is the nature of the software industry.
But that relatively small number is still enough to dominate the economy of a major metropolitan area, and so it has, and the demand for labor routinely outstrips the supply of housing for those laborers (artificially constricted, but also geographically constrained), and so those who work in software and electrical engineering and cetera can afford to live in the area. Those who do not, can not.
I look at the cities where this is an issue and I see similar threads: industries where money from everywhere flows to a relative few. Technology skims off the top in San Francisco. Finance skims off the top in New York. Government skims off the top in Washington, DC.
So the rise in visible homelessness is perhaps the expected result. Cities are economic systems, and it is easy and myopic to cater only to the demands of the prime mover. But the prime mover has auxiliaries it needs to function, without which the system will collapse.
And my experience with collapses is that they are not gradual, but rather, they are sudden.
Last night, a fire raged through abandoned vehicles parked under Interstate 280. Black smoke poured out from under the freeway and choked Portrero Hill. I watched fire crews advance on the flames and extinguish them. What will happen when the people we rely on to extinguish our flames cannot afford to live in our cities?