Homelessness, at least in the west, is fundementally a symptom of mental illness. Substance abuse may be a cause of that mental illness, or it may just be another symptom (afterall, there are plenty of drug addicts and alcoholics with a perfectly good roof over their heads). As has been said, giving them money cannot make their situation any better, and may in fact help them to prolong it.
Very true. There are loads of druggies and alcoholics with a perfectly good roof over their heads, especially in highly developed countries.

I said sometimes 'cause I give to the Redcross a lot, which pisses me off. Their all ringing their bell and they talk about on teh news how they need extra donations 'cause of all the @@@@ that's gone down and since I have a soul (don't tell anyone) I give them quarters, and sometimes dollars if I have them. I usually don't. But I get pissed when I do. 'Cause I give it to them...

We don't have any beggars here, we have homeless people...but no beggars.
At least they've never asked me for money.
I don't really know if it's possible to donate to the Red Cross in Russia. I guess you can since it's an international organization. But it doesn't really matter because I don't have a clue how I can donate some of my money to the Red Cross. I have a soul too (you can tell whoever you want about it) but I won't donate much money to any charity unless I earn loads of money not to care about the way I spend it.
In my opinion, homeless people are constrained to beg because of having no other chance to live on what they receive from the government.