It’s really not much of a shocker, Trump does self deprecating jokes all the time. There are articles written about it.
You think he's being funny, but to most people he's out of touch and regurgitates an inane and distorted sense of reality that he swallows whole from FOX. Remember his claim that wind turbines aren't safe because they kill nearly a million birds a year? That was a hoot. Cars kill about 200 million a year, but he didn't bring up that old chestnut.
But wind turbines do cause cancer, right? Wow, why didn't I think of that one! How about people having to flush their toilets 15 times because the water just trickles out. I think I cracked a rib on that one. I'm a stable genius! Ha, ha, Mr. Ed is yelling neigh! neigh! in professional appreciation...
When you tell and repeat close to 100 lies a week to national audiences with a straight face, some of them have to be jokes, right? He should probably have his own show where he can say anything he wants...wait, he already does!