One thing you realize is that a lot of the people on the streets have major mental conditions (usually schizophrenia, and major drug addictions or chronic alcoholism), and there is almost no way to just rehab them, and put them in a place that they can take care of themselves. Some of them are beyond the point of return and some need so much care, then only loving family can provide. Externally, you can't do much.
Other countries have both better mental care provided from the state, and especially a social net. Usually family will take care of their ill.
Be happy with what you got, do a good job, and make sure to be close to your family and have close friends. You will realize that is part of life, and once and a while you will have a need for support from closed ones, but as long as you an handle yourself well most of the time and try to live a good life you wont have to worry.