I've seriously suggested that the oil crisis may well play a factor.

The connection is complicated, but plausible.

As the US increased its share of oil imports, starting in 1950, its balance of trade shifted from net exporter to importer (debtor). Before the OPEC crisis of 1973-4, Nixon took the US dollar off the gold standard. I see this not so much as a problem as a response to one: it's not possible to maintain a stable currency against a consistent spending outflow.

The '73 crisis itself not only cut off oil supplies but created a huge spike in cost, again exacerbating the BoT problem. One of the critical events in resolving the crisis appears to have been a meeting in December 1973 between Henry Kissenger and the Saudi finance minister, on which I've as yet found little as to substance. A consequence of this was the "dollarisation" of the US-Saudi oil trade, later extended to the entire international oil market.

From a currency perspective, this solved two problems. The US saw a huge new demand for dollars (absorbing much of the inflationary consequence of increasing the money supply, and both government and private spending), and the Saudis weren't saddled with an ever-appreciating (deflating) riyal.

But the US and the Federal Reserve still had the problem of how to manage the money supply, and fixed on fractional reserve banking and open market operations to do so. This meant that banks and bank assets played a huge role in managing the money supply, where bank assets are loans, largely business and real estate. (Stocks and other equities play a relatively minor role.)

Appreciating real estate valuations, already attractive to banks, became even more so.

A second whammy came with the Iran embargo in 1979, by some measures more severe than the 1973-74 crisis. Meantime, increased energy costs and political shifts were undermining both manufacturing and union jobs, with them, pensions. Appreciating housing also became the household asset and retirement plan for homeowners. Toss in environmental regulations (not a bad thing of themselves) and tax revolts such as California's Proposition 13 in 1978 (a bad thing of itself), and you'd pretty much put all the ingredients together for a fatal brew.

Stew over a sputtering GDP for 50 years, and voila!

The first major reporting on homelessness came in 1980, during the US presidential election campaign, from CBS. The Doonesbury comic strip began an item at about that time, and many homeless organisations date from 1980 or shortly afterward.

There's the question of why this hadn't happened earlier. I'd largely chalk this up to the post-WWII urban exodus and suburban housing boom, throughout the US, but in particular in California, which until 1970 had never seen a subdivision or freeway it didn't love at first glance. OK, slight exaggeration -- the San Francisco freeway revolts began in about 1956, and numerous planned routes in SF were cancelled in 1959, but the movement continued to pick up steam statewide through the 1960s:

https://en.wikipedia.org/wiki/Highway_revolts_in_the_United_...

By the mid-1970s, the idea of simply rolling out massive new tract home and automobile-centred transport projects within California had largely ended. Projects could move, but took far longer and cost much more. Urban centres were already unpopular (the reverse migration into SF began in the 1980s), and there were considerable resistances to densification. What effect events such as the Loma Prieta Earthquake (1989) and Oakland Hills Fire (1991) I'm not sure.

By the mid 1990s, housing prices were taking off again, new dense construction was at best difficult, and at the same time, employment was fairly ill-defined -- California was in the process of shrugging off much defence-related activity (base closings, shifts from defence-related industry), but hadn't yet discovered high-tech. "Multimedia Gulch" (South Park, SF) was A Thing briefly in the mid-1990s, biotech was generating far more hype. There were military base closings across the state (San Diego, Los Angeles, Santa Barbara/San Luis Obispo, Sacramento, Stockton, Vallejo, Alameda, Mountain View, Concord, Fairfield/Vacaville, and more).

Then Netscape appeared and Dot Com 1.0 took off, August, 1995.