I generally reject that 'Jerry's ego' narrative out of hand. He's too good a businessman to let his $5BB product be run by a guy he doesn't believe in just because he wants to prove something. Plus, it doesn't make sense. If he didn't think he had the right guy, it's in his ego's interest to bring in the right guy so that he can prove he's capable of building a perennial powerhouse. That's much more of an ego boost than being right on Jason Garrett would ever be. Not to mention that multiple other teams were also impressed by and willing to make Garrett their HC, anyway.
The idea that we reached precipitously with Garrett just isn't accurate. Had we not hired him for the HC gig when we did, more than one other team was interested in doing so. Our fans just want to say that he wasn't ready because Jerry made the comment about having invested in his training because Jerry is an emasculating idiot sometimes.