I'm a nominal Republican, but I've been involved in partisan politics 30 years ago, and I understand the idea that politics is a team sport. There's a penalty for folks who don't get that. Cruz really did urinate away his political career, because he bit the hand that fed him. He's too much of a narcissist to figure this out. He'll get it when David Dewhurst beats him in the 2018 GOP Senate Primary in Texas.
I actually agree with the latter part of that statement. Cruz was a key figure in the rise of Trump to begin with, praising him and his ideas.
However I think you might need to understand the bet Cruz is making. He's a pretty smart guy, and must have a sense Trump is going to lose worse than Romney did. Then Republicans will say "We should've listened to Ted! We nominated this New York liberal loudmouth... of course we lost!" Then he'll run in 2020 as the white knight candidate.
That sounds logical, but it's never worked out in practice. The 1964 #NeverGoldwater Republicans saw their party getting creamed, but they were finished as Presidential contenders, whereas Richard Nixon, who campaigned for Goldwater in 1964, was a pole-to-pole frontrunner for the GOP in 1968. The 1972 Democrats for Nixon that weren't segregationist Southerners (who were already non-starters in Democratic Presidential politics) were toast afterward, whereas Jimmy Carter, a moderate Democrat who didn't campaign for McGovern but said that he would vote for him, became President in 1976 (while Nelson Rockefeller, a #NeverGoldwater Republican, was squeezed out of the VP nomination).
Come 2020, Cruz's apostasy will be used against him. Most Republicans are holding their nose and voting for Trump, and they aren't going to reward Cruz for his actions. Ben Sasse may not experience the same fate, but Sasse isn't hated within the GOP as Cruz is. Cruz gave his enemies the hammer they needed to primary him to death in 2018.
I also believe that Cruz did this really badly. He could have endorsed Trump, started to nomination fight to energize his supporters or simply skipped the Convention. By giving that speech and misleading Trump's people he just came across as a sleazeball.
If (when) Trump loses big and pulls other Republicans down, nobody is going to say that Cruz was right; he has shown himself not only to be not a team player but a clear problem inside the GOP. He is done.
