Most homeless folks these days do seem to be older than they used to be. I didn't live in an urban area as a kid, but whenever I did go into the city or visit other cities, I don't recall the homeless being that old back then. And sure enough, demographers have found that the homeless population has been aging since the start of their data in the late 1980s. See here for a short review article, or here for an NPR story with an accompanying info-graphic.
No matter when the data were collected, the peak of the age distribution consistently points to people born in the later '50s and earlier '60s, ground zero being around 1960. And it's not just a reflection of the general population's age curve shifting in the older direction. Even accounting for what chunk of the overall population is made up of late Boomers, they always show higher relative risk for being homeless. That's for the single male population, who are the majority.
Homeless families headed by single mothers (the other sub-population) show women aged 18-23 as having the greatest risk, no matter what year, hence no cohort effects. Their turn at homelessness is temporary and facultative, not part of some deeper set of traits that they have and will carry with them through life.
Before trying to figure out what about their upbringing and maturation was distinct, we should see if there's another time when the homeless were old. It keeps showing up, so you shouldn't be surprised to hear that it was the mid-century. The article above refers to studies done on the skid row phenomenon of the mid-century:
Researchers of skid row found that the population consisted almost exclusively of older, single white male households, with three-quarters of the men over the age of 45 (Blumberg et al., 1960).
So, the median age must have been higher than 45, perhaps around 55 or 60, which would place their births around the turn of the century. Just as the homicide rate was beginning to rise (peaking in 1933).
My vague impression of the tramp and hobo phenomenon during the 1920s was that it was younger and more footloose men in their 20s and 30s, not middle-aged and borderline elderly men living on skid row. This would have been similar to the situation of the 1980s, when the homeless population had grown much younger since the mid-century, and before the return back to the mid-century pattern during the past 20-25 years.
Here are a few pictures of hobos from the Jazz Age, and they look relatively young and fit, probably in their 30s, and here is a gallery of mostly mid-century skid row in San Francisco. Notice how they get older and older, with baldness or white hair becoming common by the '50s and '60s. Here is a gallery of homeless folks in San Francisco in the late '80s, and notice how younger they've gotten. Here is a representative shot of today's much older homeless, not too different in age from the man in this shot of Detroit's skid row in the '50s.
The main difference between Millennial and mid-century fates of the lowest of the economic ladder is that their standard of living was much better back then than today. Inequality was low and still falling back then. At least they were probably living in a flophouse rather than having nowhere to live, and being vulnerable to theft and violence from living out in open spaces all the time. Doesn't seem like they got harassed as much either -- "go get a job you bum!" -- and the winos were left to drink their misery away. I wouldn't want either fate, but drinking and falling asleep in a doorway sounds better than getting hostile looks in between having my stuff stolen by other bums out in the open.
What makes people born around the start of a crime wave the most likely to live a transient lifestyle, whether they were born circa 1900 or 1960? They're the first cohort not to be exposed even somewhat to the sheltering and smothering culture of a falling-crime period (Mom-ism was the norm in Victorian and mid-century times). Parents start to put away their Dr. Spock manuals and instead tell their kids that once they're 18, they're out of the house. Independence becomes valued over pampering.
And as everyone begins to emerge from their cocoons, those born around the time of the shift will assume that life is supposed to be lived out in public, not holed up indoors all day. Those born too much earlier will have experience with the cocooning norm pulling them the other way, and those born much later will have experience with the next wave of cocooning. But if you were born around 1960, your entire formative experiences -- up through age 30 -- were untouched by mid-century or Millennial cocooning. They'll feel the most at home outside the home.
Then there's the drug culture, whose trends nearly overlap the trends for crime and outgoing lifestyles. Homeless people, winos, bums, denizens of skid row usually have some degree of substance abuse problems, some very serious, making it hard to pick themselves up and lead a productive life again. Someone born around 1960 grew up unaffected by the mid-century and Millennial anti-drug zeitgeist. Drugs were just becoming popular when they were small children, and would only surge in popularity throughout their formative years. The drug culture seems to peak about 5-10 years after the homicide rate does, so that's well beyond age 30 for the 1960 cohort.
Both of these factors appear necessary -- you could always shoot up in a place where somebody you knew was letting you stay, particularly if you didn't like venturing outside. Homelessness requires not only some kind of drug habit or severe mental problems, but also the push from others and the desire from oneself to want to get out of the house and stay out there.
Nobody seems to care about homelessness as an issue anymore, as social isolation closes other people off from your view, and out of sight, out of mind. People dwell on their own troubles more, and a sense of existential malaise begins to set in. In outgoing times, people are too focused on others, including how they can help them through their troubles.
Woodstock fans who tuned out before pop culture reached its peak in the '80s might not even know about Live Aid and the other zillion national benefit concerts for famine relief in East Africa in the mid-'80s. And in fact, political content (including "social issues") in pop music lyrics reached a peak in the late '80s and early '90s. "Luka" by Suzanne Vega, "Man In the Mirror" by Michael Jackson, "Something to Believe In" by Poison, "Runaway Train" by Soul Asylum, and so on. All those touch on homelessness except "Luka," which is about child abuse.
Incidentally, Suzanne Vega was born in '59, Michael Jackson in '58, Bret Michaels from Poison in '63, and Dave Pirner from Soul Asylum in '64. It's easier to see a soaring problem when it's striking your generation-mates, and that also makes it easier to try to reach out to those who need it most. It's harder when you have to cross generation lines.
That effect is amplified by which generation is getting hit -- namely, the one that experiences rising social connectedness all throughout their formative years. If it were Millennials who had to help other Millennials, or Silents helping Silents, forget about it. But for the generation that were children in the '60s, teenagers in the '70s, and young adults in the '80s -- it's second nature to tune in to what other people's situation is, help if they need it, or ask if you need it from others.
I suppose that's another key difference across the generations too -- how comfortable are you asking others for help? Silents and Millennials are withdrawn and would see it as a sign of weakness, an embarrassment, and an awkward thing that would need to be repaid, making them feel in debt. You aren't going to get by very well as a wino, homeless, or whatever, unless you can reach out to strangers for assistance.