Ask DB, we have had this discussion for over a decade now.
It isn't expect from the fans, it's just the fans are different.
I grew up a Cowboys fan. Bought Texans PSLs. Very first season commented on how if we got down at all, heck even were leading by less than 300, the stadium had an expectation of losing. If anything negative at all happened, my Houston raised wife would be "we're going to lose." As a Cowboys fan I found it baffling. Every game was winnable. 21 points down with 7 minutes to go was still an expectation Staubach would pull it out. There is a very different culture in Houston. Not saying worse, or unrealistic - just different. Today's Cowboy fans are living in the past and yet they are still more optimistic than Texans fans.
This is what happens to the fan base when Moon is your QB instead of Staubach.