I'm a Cowboys fan, and I like Romo. Having said that, that much guaranteed money is insane.
But here's the rub...name one available option for the Cowboys at quarterback other than Romo? There's none.
Romo has played poorly in big games, we know that. But the Cowboys have so many more problems: offensive line, lack of consistent running game (DeMarco Murray can be a stud RB if he can stay on the field), and their defense not being able to stop anybody when it counted.
Here's a scenario that I used to use (but cannot any longer, for obvious reasons...).
If you put Flacco on the Cowboys and Romo on the Ravens, the Ravens with Romo are more dangerous, and are Superbowl contenders. Heck, if the Jets (during their two good years) had Romo at QB instead of Sanchez, they might have made a Superbowl (of course, Tony might have thrown three picks in said Super Bowl).
Again, my scenario is now a moot point.