As an India currently here for work in the Bay Area, when I saw the homeless people in SF, I saw scenes very similar to the ones I see back home in any major In

As an India currently here for work in the Bay Area, when I saw the homeless people in SF, I saw scenes very similar to the ones I see back home in any major Indian city. I've also seen a lot of ill people(intoxicated/under the influence of drugs?) near bus stops too. Once I almost got mugged in a VTA train station, by two teenagers. Thankfully I escaped the situation on arrival of an elderly couple in time. Like always I understand these people aren't there by choice and might have their own reason for why things turned out that way. Can anybody give a socio economic perspective on why these people are like this in a first world rich country like the US? Also the more I learn about the American culture, the more I realize the only change I see between India and the US is the infrastructure, everything else, all other problems seem to be the same. We are not so different after all.