Trump is not a politician and makes non politician mistakes but he is learning fast. You may think it is speculation to suppose Jeb would be leading minus Trump but by their actions the GOP-E shows they don’t agree with you. The GOP establishment planned to use the same model with Jeb that they used to get Romney nominated. They encouraged a crowded field to dilute the vote and allow Jeb to “run against the base” and win. The GOP-E tilted the field for Jeb by changing the primary rules this time around to make his money advantage even more of a factor. The only thing that prevents a Jeb nomination from happening is somebody with more money available getting in and upsetting that plan. Trump did that. I submit that most of the venom you see being unleashed on Trump from the GOP-E and their media minions is due to the realization that they have lost control of the process. They are showing you by their reaction who worries them the most and it is not Cruz. That should be a clue to all.
Sure Trump’s money worries them, but Cruz raised way more money than they expected. He has the war chest to be competitive against Bush as well. And Bush simply isn’t polling well. There’s no guarantee they could’ve bought the election for him with or without Trump if the people simply refused to back him.