There’s a literary trope in which an ambitious young man goes to work in the mines for a few years to earn an income with which to go back home. In the US it’s bundled into narratives of the Wild West (where incomes were very high until well into the 20th century), but it also exists elsewhere. For example, in The House of the Spirits, the deuterotagonist (who owns an unprofitable hacienda) works in the mines for a few years to earn enough money to ask to marry a society woman. The tradeoff is that working in the mines is unpleasant and dangerous, which is why the owners have to pay workers more money.
More recently, the same trope has applied in the oil industry. People who work on oil rigs, which as a rule are placed in remote locations, get paid premiums. Remote locations with oil have high incomes and high costs in North America, but even the Soviet Union paid people who freely migrated to Siberia or the far north extra. The high wages in this industry are especially remarkable given that the workers are typically not university-educated or (in the US) unionized; they cover for poor living conditions, and a hostile environment especially for families.
I bring up this background because of conditions that I’ve heard second-hand in San Francisco. When I first heard of university-educated adults living several to a bedroom, I assumed that it was a result of extremely high rents and insufficient incomes. But no: I am told a reasonably transit-accessible two-bedroom in San Francisco proper is $5,500 a month at market rate, which is affordable to a mid-level programmer at a large tech firm living alone or to entry-level programmers (or non-tech professionals) living one to a bedroom.
And yet, I’ve heard of Google programmers living two to three to a bedroom in Bernal Heights, not even that close to BART. I’ve also heard a story of people near the Ashby BART stop in Berkeley renting out their front porch; the person sleeping the porch was not a coder, but some of the people living inside the house were.
I have not talked to the people in these situations, only to friends in Boston who live one person (or one couple) to a bedroom, even though they too can afford more. As I understand it, they treat the Bay Area as like working in the mines. They earn a multiple of the income they would in other industries with their education and skills, and have no particular ties to the region. (Some East Coasters have taken to use the expression “drain to the Bay,” complaining that friends in tech often end up leaving Boston for San Francisco.) The plan is to save money and then retire in their 30s, or take a lower-paying job in a lower-cost city and start a family there.
Overcrowding is not normal in San Francisco. The American Community Survey says that 6.7% of city housing units have more than one person per room (look up the table “percent of occupied housing units with 1.01 or more occupants per room”); it’s actually below state average, which is 8.3%. Some very poor people presumably have more overcrowding, especially illegal immigrants (who the census tends to undercount). Figuring out overcrowding by demographic from census data is hard: the ACS reports crowding levels by public use microdata area (PUMA), a unit of at least 100,000 people, and the highest crowding in San Francisco (13.7%) is in the SoMa and Potrero PUMA, which covers both the fully gentrified SoMa area and poorer but gentrifying areas of the Mission. But it’s conceivable that crowding levels among tech workers are not comparable to those of the working-class residents of the Mission that they displace.