There's plenty who love booze and drugs who aren't on the streets though Voltaire. I can't imagine anyone choosing to sleep rough where you're exposed to the elements and all manner of abuse for begging. Especially in Winter. There's all manner of reason why people end up in such situations from broken homes to mental illness, do you disagree? Of course I'd sooner have these people get out of their situations as I wouldn't wish what I've seen on anyone. I don't equate humanitarianism with Christianity either although they certainly share certain characteristics where it comes to ones fellow man.
There may be plenty of people who love booze and drugs who are not on the street, but plenty of people who are on the street cannot give up their booze and drugs. You may not be able to imagine anyone choosing to sleep rough on the street, but somewhere in their mind, they did just that. They added up the pros and cons of getting a job and giving up the booze and drugs and being responsible with their money and essentially giving up some of their freedom to do what they want with their time. Somewhere along the line, they decided that the "consequences" for doing the latter were just too burdesome and unsatisfying, and as awful as sleeping rough on the street was, it was much better than the alternative.
Yes there are all manner of reasons why people end up in such situations, but you seem to think all of them are a result of circumstances beyond the control of the people involved. If you really wished these people could get out of these situations, you would not be so reluctant to believe they do not have sufficient motivation to do so in many more occasions than you currently think. You don't equate humanitarianism with christianity? You and many others on this board seem to. Truly helping people goes far beyond filling their bellies.