And you’re not obliged to. There’s nothing immoral about not going out of your way to help people especially at risk to yourself.
While they are people and should be treated with dignity and not like animals, they are still people and like any stranger can be dangerous and unpredictable, especially in desperation.
Not to mention at least near where I live about a third of the homeless are mentally ill due to the state’s incapacity to care for such people.