"In my estimation" implies I'm going off personal experience. Right?
Mental issues is what I actually said. Either way, these people still make choices, many bad ones. Maybe my definition of mental issues is a little broader than your mental illness term. I don't believe it's simply people who drool on themselves. For instance, if you voluntarily live and $hit on the streets of San Francisco because you can't afford rent, when you could eek out a living somewhere else, you clearly have mental issues. Your priorities are clearly not in line with society.
Monetary homelessness should be very temporary. Kicked out of the family home, temporary. Lost job, temporary. To permanently find yourself homeless and needing constant assistance implies there is something wrong with you. And I'll go a step further, it probably implies you've refused to get the help you need many times over. I'm not religious myself, but I know churches have always reached out to people in this way. Even if you don't believe, they will help you. Even most local governments have some small operations. If your not willing to adjust your lifestyle, or whatever it is for the sake of survival, you have issues. That's on you and often a choice.
This is coming from someone who hands out pocket change quite frequently. Some of the people you think are homeless are not. They make ends meet through panhandling and appearing homeless.
Anyways, these types of studies are highly variable and individually unreliable because it requires honesty and can't be truly observed. Human error right? I wouldn't expect every drug user to admit they use, would you? That's kind of common sense stuff.
I'm not degrading these folks, but I can tell by your line of questioning your not fond of my take, so what are your thoughts on the topic? Rarely do you actually give those.