We really need to face the reality that it's too late for that, now. Very, very few gangbangers, drug addicts, or homeless crazies are EVER going to rejoin society. There is no "fixing" this. Once we've locked people out of 'normal society', and they've accepted their fate, they aren't coming back. Who even wants them back, really? We didn't want them around in the first place. It's why they are where they are.
So now we have to decide what we're going to do about all these broken people that we've created because of our greed, and our bigotry, and our selfishness, and our willful ignorance. Because their numbers have grown massive and we can't keep ignoring them, anymore. Our cities are fulling up with them. Our small towns are choking and dying all across the country from poverty. Thousands and thousands of them. And the people still living in them are getting more and more 'broken'. From drugs, and alcohol, and hopelessness.
We still don't seem to understand that this can't be fixed. And it's going to keep getting worse. The solution was not to push those people out of our society in the first place. But we did it, anyway. And now here they all are. Doing whatever they have to do, to survive.