The problem is a bit more nuanced than it first appears.
We need to look at how people live to understand what costs are involved in that living. Poor have always existed, to be sure, but the structure of communities has also changed over time. Looking at small townships and boroughs throughout history, you see societies operating far more off of what is considered "social credit." Rather than a literal barter system where payment is exchanged up front - the community generally barters goods and services within itself without much logging and cataloging of debts. Money was reserved for exchanges outside of the community, itself usually no more than the troop size layer of the Dunbar Layering system in humans.
Families often developed estates - many generations living together under the same roof. Women typically remained in the community while younger men would travel into larger cities or to other communities to perform paid labor or other services. This was especially the case during the Industrial Revolution. Cities, themselves, have always been more complicated affairs as space has come at a premium. Where people in the townships would often grow their own foods and land was at far less of a premium (while legal claims to land could be vast, most areas honored a sort of tenancy law where land not actively maintained by an individual could be lived on and eventually claimed by a person who could prove they were maintaining it) - cities often exchange in a monetary currency because the individuals are unknown to the people overseeing the transaction. Space is at a much higher premium in developed areas and rent has usurped ownership in many regions.
Because of often legal constraints on urban development, rental enterprises are rarely challenged within the free market. This is particularly true when federal housing subsidies are taken into account and there is no reason for any person owning a rental property to ever charge less than the federal rate. Where, in a free market, homes or other spaces would be built to satisfy demands of those with jobs and money, in a more legally constrained market, there is no reason for a rental property to aggressively price. Once the building has been paid for and modest maintenance costs are taken care of, a rental property is a money mill. $500/month is a relatively low rent here in this region, and you figure an apartment complex with over a hundred renters that may have only cost a few million to build.
This is a key problem, where families used to accrue wealth across all classes, it has now become much more difficult for families to accrue that wealth, particularly as our culture insists on children perpetually fragmenting from that family base. Then, we must consider the concept of what they are fragmenting to go do. Education has become entirely inflated in cost relative to what it does. The problem with college, particularly in the wake of the internet, is that it is little more than a paid credential. Go $120K into debt, be certified that you played the game and can be hired by other people who place stock in the importance of that game. The field of education has been bastardized to such a point that it is no longer about what you know or can do, it is about where you spent money and how much of it.
All of this leads to yet another problem. Our currency is all debt based. It is perpetually losing value, even when it is 'stable,' it is only doing so in relation to the precipitous fall of other currencies, internationally. Against the hard, material products - the purchasing power of our currencies is always in decline. I can remember going to the store in 2008 to buy 2 liters of soda for $0.75 and $0.99 depending upon what brand had the deal going at the time. These were Coke and Pepsi products. Over 100% inflation in price within 10 years. True, not all markets inflate equally, but the problem is that the costs of living are continually increasing while the purchasing power of bank accounts and paychecks declines.
The only way to protect against inflation is to get rid of the hot potatoes - the currency, itself. Purchasing assets that are denominated in currencies, as opposed to holding the currencies. Assets hold an intrinsic value - they are what we spend currency on or show up and go to work for. These assets protect against inflation, and those who have been able to acquire enough currency to purchase sufficient assets are part of an "asset class" in and of itself. These are the people who own factories, rental buildings, etc. Not all of them are bad people, but placed into perspective, the working class has been effectively rendered servants within debt and credit fueled economies backed by central banks (federal reserve).
As such, while many who are poor or homeless do also have accompanying mental health issues, it is also true that we have vastly complicated the costs of living to create an ever expanding category of poor within society. This has then been coupled with a controlled opposition philosophy - socialism - which is the same stated of service re-branded to appeal to those who are displeased with the current arrangement.
