". . . but mostly it is [their fault]. . . "

Statistics? Source? For one thing, the question is about public property, not "the lawn of your home" (private property) so that is irrelevant. Second, I have been homeless myself and I will concede that many in such a predicament do have mental illness... but contrary to common lore, most are not lunatics running around chasing people. The vast majority are people who are mentally broken, exhausted, and afraid. It's NOT a fun or desirable way to live. And I promise, there are millions more people that are NOT homeless, like…  Read morely in your neighborhood too, who are using drugs in their homes, or drinking away their pain, or are lucky enough to have health insurance to get treatment for THEIR mental illness. The media and the government have painted a broad brush indeed that all homeless people are crazed, psychotic drug addicts. Don't believe everything you hear.