I get more than a whiff of morality being correlated to income, and a lack of respect for the winds of fortune here. The idea that good people work hard, and hard work is rewarded, therefore only bad people are poor and it's their own punishment.
It's one thing to be poor. It's quite another to be homeless. Also, don't forget that at least for a while we are still free; the homeless are not destined to stay in the gutter if they don't want to. We have no castes in America.
That's a nice, but false, sentiment (that we don't have castes in America). The castes in America are more subtle and fuzzier than those in India, but that makes them no less real.
The reality is that the vast majority of the chronic homeless are both poor and physically or mentally ill (or both). It's a natural consequence of the closing of so many mental institutions (which in and of itself is not a bad thing) without providing alternative treatment and housing options (which in and of itself is a bad thing).
Add all of this to the fact that it is by and large expensive to be poor and you end up with large groups in America who are unable to shift their fortunes in any meaningful way.
Yes, there will be a few fortunate individuals that manage to claw their way out of being poor in America (and they will be held up as examples by all sides, missing the point that they are the exception for a reason!), but in general people who are poor in America stay poor in America.
[I suspect that one could substitute "Canada" or "France" or "England" or most other Western countries for "America" here, even if the problems and reasons are slightly different. Toronto has a substantial chronic homeless problem because of idiotic downloading of social programs from the province to the city and subsequent reduction of mental health programs. Note as well that I'm differentiating between chronic homeless and temporary homeless; your statement about "not destined to stay..." is true for the temporary homeless. The original article is mostly about the chronic homeless.]
Do you have statistics on homelessness before the mental institutions were closed down? Obviously we'd need to find a way to time-adjust them but I'd be curious to compare.
The general impression that I've obtained in my casual reading of this over the years is that (a) there have always been "indigents", but (b) the numbers have gone way up since the 1960s and (c) a disproportionate number of "indigents"/homeless have been those with mental illnesses.