Would a simple solution to this be to say plan a date each year to give away some quantity of money? You could keep a record of all the times you gave money to a beggar, or you could use a simple model to estimate how much you probably would have given, then you can send that amount to a worthwhile charity.
When I get more money that’s what I plan on doing.
I am uneasy with that sentiment although I’m having a hard time putting my finger one exactly why. But this is how I see it: there are vastly more people in the world than I could possibly ever help and some of them are so poor and downtrodden that they spend most of their money on food since they can’t afford luxuries such as drugs. Eventually, I might give money to the drug user if I had solved all the other problems first, but I would prefer my money to be spent on something more essential for survival first before I turn to subsidizing people’s luxury spending.
Imposing my values on somebody seems to more aptly describe a situation where I use authority to compel the drug user to not use drugs.