Many homeless people are kind hearted and are just in need of help. However, there are many who don't want our help and are threatening. I think that we should help those who want it and only fight those that pose a threat to us. When you look at a homeless person, you should never generalize them as violent or mean, just because of how they look.
All we can do is lend a helping hand.
A great many of our homeless here in the USA are mentally ill, whether they be self medicating with booze and drugs, off medications essential to basic functioning (such as the case of paranoid schizophrenia etc), or veterans suffering the consequences of war.
Currently, there are very few appropriate long term treatment centers for these folks, and our laws are written in such a way as that it's very difficult to force a person to seek treatment, stay on that treatment, or institutionalize against their will whether it's "better for them" or not.
The best we can do is make resources available, through private charities and volunteerism, to help those that want it.