Why is the felon walking out on the White House roof? To show people he wants to impress how much he owns? Because he wants nukes there, just in case?

No. It's a place to throw people, like under a train, under a buss, under a truck, out of a window.

The White House isn't high enough to certainly kill. A victim will probably suffer in lingering pain before dying, and the felon might want to watch that.