Why are so many veterans homeless?

Because we are both "the land of the free" and "the home of the brave". We have lots of charity, social, and welfare programs to help those who want help. But those who choose not to take it (often because of alcohol/drug use, mental illness, or plain life style choices) are "free" to live their lives as they choose. Unlike other countries, we don't institutionalize the mentally ill, imprison the poor, or send the lazy off to labor camps.