> because I don't know if they will commit crimes. It's not a given, it's a decision they make
This ALSO applies to drugs.
You don't know if they'll use drugs, you just assume. And it's a fair assumption.
Symmetrically, you can't claim you don't know they'll turn to crime to fuel their addiction. It should be a fairly straight forward conclusion.
It's a matter of cause and effect. Your own personal moral code is irrelevant. We know, whether we want it to be this way or not, that it's extremely difficult for drug addicts to stop using, particularly those with zero resources like the homeless. It's just the reality, and we have to live and operate within that framework. Because any other framework is make believe.
> because no one is responsible for their decisions; we're all just flesh automata animated by neurotransmitters
I'm not claiming this, you're doing the typical thing where you take my argument to the furthest extreme and then claim that is actually my argument, so it's easier to disprove.
The truth is choice is tricky. It's not binary, it's continuous. There's infinite levels of influence we have in each and every aspect of our lives, even the smallest ones. I can choose to, for example, not brush my teeth this morning. Would it be easier, or harder, to choose to not do heroin, provided I'm an addict? You know the answer.
My main argument is that you're not an enabler by giving them money because ultimately your influence is minimal. You're also not an enabler by NOT giving them money. Their "choice" (loose) to use drugs is due to societal, biological, and economic factors, which you cannot control. If you simply do not provide them money, even if everyone did this, you would not rid the world of drug addiction. In addition, you have to understand there's a reason these people do drugs. They live very hard lives. It's pretty easy for us in comparison. I can't blame them for craving an escape from the reality they live in. It's hard to look to the future you can build when you have no present.