It's incredibly privileged and reductive to think of it that way - that, after surviving in a park for 10 YEARS, struggling for food and shelter, surviving the seasons, rest of society and getting beat down to square 1 so many times -and basically being in constant fight or flight mode as the article states - you think you wouldn't resort to escaping through alcohol or drugs, and could simply "decide to get your act together" and adapt to anything the govt agencies expect from you on daily basis in some of those housing solutions.
Those people did not cheerfully decide one day to dedicate their life to shitting all over a park and be addicted to meth. A lot of homeless people got there either by being let down by the society very early on, or by 1-2 bad events in life making it impossible to pay rent and getting dragged into a downward spiral from there.
Solutions should be focused on the root causes, and not the symptoms. If the country is such a late-stage capitalism shithole that so many people are 1 medical emergency away from not being able to pay rent, and there's no safety net or effective government support to prevent them from going homeless, the cost of trying to rehabilitate someone after years on the streets / in the parks is going to be multiplied. I'd like to see how those large budgets are being targetted first at number of new people coming into this situation being reduced, and then additionally decreasing the existing homeless population.
As usually, there are methods being successfully (at least to a larger extent) used in other societies - but USA is very often dismissive of them, because it's special and different.