Mental illness

There are always cases that people who have mental illness, they are either hurting or even killing people are acquitted in the end, ridiculous!
I mean, yes, they don't know what they are doing is wrong. But why are they wandering on the street on their own in the first place. And get away not guilty while other people lost their love ones.
If they cannon be cured or be taken good care of!? Why still they exist to destroy others' lives!? 

Life imprisonment, one thing that I never get over it! Really, they are so guilty, so they can stay alive in prison all their lives with free food and board. Don't mention that there are chances that they can out of the prison somehow.

Another is, what on earth is teachable criminal mean!? Therefore, they can walk away free!?
Surely there are few cases, they returned to normal life or even helping others in need.
How many are there!? Most of the cases they committed crimes again and again. Some even became worse and damage a lot more innocent people's lives!

I remembered years ago we were in line to buy lunch at El Pollo Loco.
A Hispanic obesity young man pushed me hard with no reason. I was shocked and almost fell.
His parents, the store employees or anyone in the store didn't say or do anything with it.
Only I was younger back then so I could walk away in one piece.
If the people was being pushed was an old person, they probably fell and severely injured. Broke a bone or two or die or became paralyzed!
If the people was being pushed was a kid, she or he may be traumatized. She or he may be scared of Hispanic obesity young man! 
Why are take him out and didn't take good care of him!? Why have you fed him to obesity!?
He was at least twice about my size! They get free money from government for raising him while a lot of others starve or homeless with no money! It doesn't make any sense to me!

I understand that this individual is a life too, like you and me. Also, it must be a torture to have him and take care of him.
But remember you are the one to make the choice to spare his life and you took the money, then that is your responsibility no matter what! Or else!