Very similar things happened to me, years ago.Good point. That seems to be a common attitude with homeless people. I can find a little sympathy for people who have hit rock bottom, even if largely due to their own doing. But that sympathy evaporates quickly when someone has an abrasive attitude as cherry on the pie.
I had a shitty experience like that on one of my trips to Canada. After a good day of business, I treated myself to a nice dinner in one of Montreal's great restaurants. Came out of the place feeling good and on my way to the car I passed by a homeless guy, who was sitting on the sidewalk. I has $15 cash in my pocket as change from the restaurant bill. Felt bad for the guy and handed the $15 dollars to him. He looked at the money while I walked on and he yelled at me: "Why dont you give me $30?" It must have been 4 years ago, but it was the last time I gave anything to a homeless person. And as we say in this hobby, I will not repeat.
I was at a McDonald's and a homeless man asked me to buy him something. I said, "sure", and he said he wanted a Big Mac Meal, plus an extra Big Mac. That was more than I was willing to get him, so I said, "That's too much, can you just get the Big Mac meal?" And he shot back, "That's not too much!" I just ordered my meal, and left him there. He became angry and upset. I felt very bad, but I also was so turned off by his entitlement and lack of gratitude.
Today, I feel guilty. It must be incredibly difficult to be homeless and I had the opportunity to bring a bit of joy in his life. He may have been really hungry, or just wanted to save the other burger for later. And in all honesty, another $5 would not have killed me. Homeless people are homeless for a reason, sometimes it's a mental issue. Not all of us are fortunate to not have mental disease.