Earlier quoted context omitted.
While violence is sometimes justified, I think it's still better to build a society that tries to solve its problems without violence or prevents problems that can only be solved with violence. When you have reckless people attacking the elderly you need better psychological healthcare and a better social system to prevent that. I understand your point and in a narrow context it's definitely true, but in a larger con…
What about the people that are violent, not because of mental illness, but because well, they want to cause others pain?
Most people doing evil things are in part doing these evil things as a result of their circumstances. By changing their circumstances through social programs you reduce violence and make everyone happier as a result.
You can argue that blaming violence on circumstances ignores people's own responsibility, but I believe that better social and medical programs are still worth it because they attack the part of the root cause society can influence most easily.