We don't need more money, we don't need more programs. We need an implementation checklist.
You see, we as a society need to take it step by step and adopt a scientifical method in dealing with this problem. The first step is to prevent the mentally ill and drug-addicted from being a danger to the community and to themselves. So bring back the institutions as that first step.
Then a second step, we need to identify groups of people that we decide to re-introduce with "community care", monitor their results and keep them accountable. Each one of them will most likely respond differently to different implementations of what you call "community care". Give it a time duration too, and observe the behavior. And so on.
Finally, there will be individuals fully re-introduced into society. There will also be individuals that need a little bit of extra effort to make that happen. But like with any group, statistically there will be individuals too dangerous that must stay in the institutions for their own health.