A lot of people got screwed along the way
whether people should be able to hold on to that billion is a different question
Having these discussions in this current cultural moment is difficult. I'm no lover of billionaires, but to say that every billionaire screwed people over relies on esoteric interpretations of value and who produces it. These interpretations (like the labor-theory of value) are alien to the vast majority of people.
the wonderful thing any capitalism is that you can absolve yourself of guilt by having someone else do your dirty work for you. are you so sure every single seamstress that made clothes and stuffed animals, and the workers at the toy factories, and every single person involved with the making of the movies for the Harry Potter deals she licensed her work to were well compensated and treated well? that's not directly on her, but at least some of her money comes from there