Well, the point was, I feel no need to give anything to the homeless.
That's because you're young. No offense, but your attitudes and values will change over time.
Wait until you have a kid... Your outlook on how people treat children may change dramatically the first time your mind wanders and you imagine what your kid's life would be like if you were not there to take care of him. Or how your kid would feel if someone abused or intentionally injured him.
Then of course as your kid gets older, and you see how he lives, succeeds, and fails, you will see that same bum and wonder if years ago maybe he was some kid, like yours, who didn't get a chance or was abused/neglected/whatever. And maybe you give the guy a few bucks because you can't change his childhood but maybe you can make him a little happier now.
Or not... Some people don't ever get it. But lots of people do, some instinctively and some through their experiences.