Did he really think he had a chance?
No, he was just there to help Jeb, in NY mainly. Jeb's only chance was with a lot of candidates, so he could be the frontrunner with 15 or so percent. Trump blew that plan away, and with Pataki at around -1 percent in the polls, he was no longer of use to the GOPe, and they decided not to waste any more money on pretending he was running.