O'Donnell said she would leave the country if he became president. When he became the presumptive nominee people asked her if her bags were packed and she said she didn't need to because he would never become president. Trump said that if she did leave that would be a great thing for America. This is your evidence that he has thin skin? I just don't see it the same way at all.
I think it's evidence that he's a media whore who will stop at nothing to keep the spotlight on himself. I see his bizarre faces during the debates and the vast majority of his tweets the same way. Every time the spotlight turns away from him he will do or say something that will cause it to swing right back. I agree with you that he is incredibly arrogant, and I would add that he's a complete narcissist. He could tell you one lie in the morning and a completely opposite lie that evening, and he'd believe both. Not only that, but if you called him on it he'd attack as if you had eaten his firstborn.