Don't underestimate the ego factor
Right, so why is Haley sticking around if Trump is the presumptive nominee? We've put together a few hypotheses — spite, in case something happens, sticking it to the man etc — but, as ever with politicians, we cannot discount the possibility that she's in it for her. I keep thinking of Beto O'Rourke's "born to run" comments in the 2020 primary. A lot of politicians think this way!
—G. Elliott Morris, 538