There is an elderly man begging for money that I am going to ignore.
Why? Is he begging you specifically?
He just asks for money to get drunk again.
There is nothing wrong with ignoring people who's asking for money. You'll never know what they will use it for.
It's so likely that he will use it on alcohol. It's a waste of my money. But I do worry, what if he is starving?
Well you have to make a choice without knowing what he is going to use it for. But you are not doing anything wrong by ignoring a beggar, you are under no obligation.