Well I'd say Obama has put more effort into his presidency than trump ever has, gotta count for something. And uh, I wouldn't necessarily call this term a peaceful one. Trump did in fact think that everybody thinks the deserved the peace prize, and you'd be foolish not to believe he didn't either, just based on a already shaky summit. I feel more at ease if Obama got a prize for no effort rather than Trump getting it for no effort and he's a habitual liar and hypocrite, among many other things.
Well u cannot say Trump asking for Nobel Price when he never asked. And also this summit is Kim Jong un calling not Trump. There are no peace negotiation to begin with, US asked NK to denuclearize since Nixon but only in Trump era NK start to open and show a willingness to denuclearize. And Trump with his Fire and Furry style threaten NK and it worked. This drama is just part of his style in negotiation. Trump might be hypocrite or bad in the eyes of many , but for now it seems he done well to make NK open up and make the first move. He might be crazy but as crazy it gets i think he is the leader that USA need at this moment.