What is the main reason for people becoming homeless?

The main reason that people become homeless is because they no longer have a home.

The reasons as to "why they not longer have a home" are vast and varied including lay-off, staff reductions, terminations, various dependencies such as drugs, alcohol, gambling, shopping - mismanagement of funds, foreclosures, poverty, eroding work opportunities, decline in public assistance, lack of affordable housing, domestic violence, lack of affordable health care, mental illness, etc...

This is a very complex issue and unfortunately there are no easy answers.