Was the terrifying acts in Macbeth free will, fate or the hysteria of crazed circumstances?

I think Macbeth's demise was largely to do with free will. You need to consider that nobody made Macbeth do anything. The witches merely made suggestions they knew would mess with his head. They were witches, that's what they do! Macbeth's tragic flaw, all protagonists in  tragedies have a tragic flaw, is his greed and ambition combined with the fact that he is kind of a coward. He stumbles his way through successive murders until he becomes King. Unfortunately by that time, he has pretty much sold his soul and become a socio-path that nobody likes.