I think he’s doing it for publicity plus options depending on how things go. In other words, I think he’s keeping the option of SERIOUSLY being president if it looks like he has a chance.
Trump has something more up his sleeve—I bet he will enter the race -—at least for a time before he’s knocked out in the early primary’s -—In the end this could help him. He has something else planned to un-mask Obama and help bring him down. He might be doing it to help Hillary—an old friend, or Sarah Palin, a new friend. Or maybe both! In the end he will help America (and himself).