What they are not sufficiently concerned about is that Mr. Trump has not expanded his popularity. He has kept his core but failed to reach out consistently and successfully to others. He has not created coalitions.

His position is more precarious than his people see.

He has too much relished the role of divider. When you’re running for office you are every day dividing those who support you from those who don’t, and hoping your group is bigger. But when you win you reach out to your enemies with humility, with patience—with love!—and try to drag ’em in to sup in your tent. You don’t do this because you’re a hypocrite but because you’re an adult looking to win. Or a constructive idealist. That happens sometimes.

His supporters don’t know what he doesn’t know: He must grow or die.

They are happily watching The Trump Show as he sticks it to people they hate. They don’t know Shark Week is coming.