Homeless people often aren't homeless because they lack homes. It's a very loaded and misleading term. There are usually many other problems that they need help with, and homelessness is often just a symptom.
And I'm no expert, but I imagine there's a circular relationship between the issues that homeless people have. Not having a home often means no address (unless they're able to access a PO box or similar?) so difficulty receiving mail or getting a bank account; it can mean less physical security so a higher risk of being a victim of crime (e.g. theft, assult); a higher risk of problems with the police; probably greater risk of ill health due to living conditions; and far less psychological security - to name but a few.