Narcissistic Personality Disorder. Every time I see these little habits (and it is little in the larger scheme of things), the only thing that makes sense is NPD. He has needs, however petty, and that is why he engages in senseless twitter arguments and continues to rage about his inauguration crowds and had his electoral map framed. Rowling is right--he's a "tiny, tiny, tiny man" on the inside and compensates for it on the outside.