You have to remember this is a revolutionary election. There has been nothing like it before. The people are not supporting Ryan. They are supporting Trump as long as he sticks to the issues he has already stated,.Only because he wanted to, not because he was made to.So was Boehner and look where he is.Trump will kneel before Ryan or not be president.
That simple.
Ryan is the King Maker.
He was going to give it to Cantor, but one of the few TPM upsets occured there.
So he picked a successor.
This election in the GOP side is played by Ryan's Rules from now on.