Obviously this is a hilarious and obvious lie but it's instructive in that Trump knows he's supposed to care about this thing, and manifestly does not and cannot care about it, and so he has to put himself into the story just to make it something he can talk about. He almost died that day!
Trump on 9/11: "I just thank my people. I was building a big building in New York & I took the whole crew down there right after this happened & they had no hesitation. Everybody went down with me... we thought it was coming down on top of us... two fireman lifted me up and started running with me"