be allowed to continue whatever pattern in their life led to their current circumstances?

you're speaking from complete ignorance.
drug addiction in america is already a disability and you can get section-8 housing for it... it's just a shitty little one bedroom apartment...
and people still use drugs in there. the major difference is: they're not shooting up at the bus stop and sleeping there...
they also have access to safer things like methadone and people are able to reach out to them.
when it comes to "these whatever pattern led to this", you're using blame-the-victim language. most homeless people have mental health issues... other disabilities, or just fell on hard times.
but most if these problems can be helped, and these people are better able to help themselves when they're not spending all their time looking for food.
consider how likely you are to "get a job" when you walk into a place with a backpack, dirty clothes, unwashed, and completely shellshocked from sleeping on the streets.
it can definitely be done, but that requires a lot of things that most homeless people simply don't have...
if you meet these people's basic, most minimum, lower level of maslow's hierarchy, then they can begin to think about the other problems that led to their patterns in life.
if they're content with some little apartment and minimal food and whatnot? then that's not really a big deal... let them live

it's not at all what you imagine. people aren't out there because they're lazy.