Why doesn’t winning generate revenue / increase valuations? And if it does, then why isn’t that his strategy?
That's fan logic, which is what we always use, but that's not the logic that Jerry uses.
Make no mistake, Jerry knows if the Cowboys were to win a Super Bowl, both his revenue and team valuation would increase considerably.
The problem is that Jerry is a businessman and he knows that 80% of potential is better than 50% or worse. To him, the risks-vs-rewards of the remaining 20% of the 100% a Super Bowl would bring does not offset the drop that a failed attempt would bring.
Jerry is quite content with 80% being the reward for failing, but after 28 years, 80% is becoming more and more unacceptable to fans.
At least with a 50% or worse season fans would get a rebuild of some kind. 80% makes it too easy for Jerry to think the Cowboys are one or two players or one or two lucky calls or bounces away from success, so he just rinses and repeats year after year.