AGREED!
But they can't. By backing Cruz, some of them are taking a calculated risk that either (a)they can get their brokered convention and pull the rug on Cruz at an opportune time to put in someone they can trust like Kasich or Rubio or (b)they will be able to control Cruz with donor money.
It is entirely possible that Cruz understands this and is playing them. Think back to three months ago where Cruz and Trump were on the best of terms and wouldn't even criticize each other. It makes more sense to think that then was the real thing and now is the Kabuki Show rather than the reverse.
Look at it this way: In 2008, McCain was their designated loser and Romney or Huckabee was their back-up plan.
Now, the shoe is on the other foot.