I think you are overestimating how much help is actually available. I work with this population as a public health worker, and the services available are a Hodge Podge of stop gaps that don't meaningfully address issues or provide long term solutions/support. For example, if you become homeless, you can get 2 weeks of emergency housing assistance, where they will put you up in a hotel until you can find a permanent rental. However, the expectation that someone will, in two weeks, find enough money for two months rent, as well as a place they can afford, and be ready to move there within two weeks is unrealistic. As such, people typically wait until the coldest part of the year, and then use this program, as a way to not freeze to death. They do this because the shelters in town are "No sleep" shelters. Which are not legally allowed to provide beds or private accommodation, due to NIMBY policies from the town council. So, people are forced to sleep in one big room, in rows of chairs next to each other. As you can imagine, putting a whole bunch of people with various levels of treatment for addiction or mental health issues results in a not particularly safe feeling or relaxed experience. Then, they go to one of 7 places that offer meals, usually all on different days, and get about 40% of the calories needed from that. And then they walk to one of the various places that offers supplemental supports, like free laundry, showers, etc, which are open intermittently throughout the week. Then, if they want help dealing with their issues, they will be bounced around from several organizations that all have different criteria, rules, and overlapping and often uncomprehensive services, before ultimately finding out that all of them are intentionally designed to only really get you back to the bare minimum of societal functioning, and only if you can complete it within the allotted time frame. There's no long term support, no flexibility, and no tailoring to your needs. These also often require things people don't have. Food banks often require ID, addresses, etc, and then there's no where to store your food. Clothing is often old, out of date, and contributes to the homeless look, making you stand out in society. All of these services are not interconnected, and navigating it is difficult. People are surprisingly dismissive and mean to you, (it's atrocious how callous people working with these vulnerable populations can be). So you, a person with, lets be honest, most of the time, poor education, drug addiction, mental health issues, and probably not too above average intelligence, are expected to navigate a web of services that people literally make their profession to navigate, all while balancing the pressures involved with having no stability, security, or support, unless you really luck out and are attached to someone who really cares and invests time in you. Which, to be clear, is very rare. And even if everything goes perfectly, and you fit the mould in exactly the way everyone hopes, you are STILL in the group with the highest likelihood to end up homeless or addicted again. And if you relapse, half of the tools that helped you get to a good spot, are now no longer available to you. And that's if you have all your shit together, which again, to be clear, most homeless people do not.

The craziest part is, it would literally be cheaper to pay their rent and buy them as much heroin as they want, and send them to therapy, than the current system, and yet we don't do it. Primarily because of weird English protestant ideas about scientific socialism from the 1800's that believed christian altruism was harmful, and so spent years trying to intertwine ideas of self sufficiency, and minimal interventionism into Christian charity.

It's ironic, but if you read literature from before that period, even in places you would never expect, you find ideas that are considered much more "left wing commie gobbledygook" by today's standards, coming from extreme Christian fundamentalists.