Just to get you up to speed on Trump.
1) He's 69 years old. He has no ulterior motives, politically or financially : he's reached the age at which people look around and go -- "what is life going to be like for my kids and grand kids?" and he just noticed how much American has been fundamentally transformed by the Bamster.
2) He's a billionaire. He doesn't need the money, fame, connections, or ego boost.
3) Megyn's attempted shaming question about 'it would be a pretty picture to see her on her knees' was hopelessly inept: have you seen the women Donald Trump was married to? Obviously, she should have asked that question of Hillary, and asked how Hillary could talk about #WarOnWomen given her unwavering support of Bill after all he has done.
To me, Megan Kelly's question did come across as petty.