In my experience it's very hard to prove to the standard required for the authorities to intervene. Basically you have to wait until they have already hurt some

In my experience it's very hard to prove to the standard required for the authorities to intervene. Basically you have to wait until they have already hurt someone before action can be taken. And it's even worse if they are only a danger to themselves. Worse still if they are simply incapable of sustaining themselves rather than actively suicidal. Believe it or not many of these people have relatives and friends who do care about them, deeply, but are powerless to help them because in their delusions they have violently rejected their help. I've watched a friend of mine starve nearly to point of death on the street and be unable to do anything to help him other than take him to lunch whenever I could.