I still think he has the easiest road to the nomination. But he’s starting to remind me of that guy Russell that played 3 or 4 times on Survivor. He back stabbed, lied, essentially cheated - did anything he could to make it to the finals. He ticked so many people off along the way that he lost each time in a landslide because nobody liked him. Life imitates art. I see the same thing happening here. He’ll get the nomination, but at what cost? And never be able to repair his image enough to beat Hillary. They’ll brand him an fear monger, a racist, a bigot, a woman hater, and it will stick.
But politics isn't like that, at least during the primary. Because you end up needing the support of those opponents and their supporters in the general election. And as irrational as it may be for people to not vote for him out of spite, some people will do it anyway.
And that's not even considering that if he doesn't get to 1237, then how other candidates and their supporters feel about him is going to matter very much in those subsequent ballots. He may actually be blowing that right now.
I'd suggest the cost you refer to is self inflicted. He has a not insignificant delegate lead, and a opponent in trouble himself. If he's concentrate on issues, and expand on his positions, I think the nomination would be his, and he could run for President rather than reality show host. This may be a personality issue rather than poor strategy, in which case the dem's might have a chance with the two weakest candidates I can recall.