That's what he may think, but it's more likely that people do give him chances and he doesn't use them wisely. You were there for him and he took advantage of your kindness by dumping out his frustrations on you, making unwanted romantic advances, and then getting hostile when his attempts were rebuffed.

When was he a good friend to you? He is very concerned with how you treat him but he seems to have no care for how he treats you.

I wouldn't even bother getting into all of that with him, personally. You tried to be there for him but he did not want to accept what you were offering. It is entirely okay not to respond to his messages.