If you showed up on a Raiders, Bills, Jaguars, Browns, Texans, etc message board and said that you expected the team to win the Super Bowl and otherwise the season was a waste I'm pretty sure you'd be laughed off the board. Most Americans have the critical thinking ability to understand that reasonable expectations are connected to a massive series of factors rather than just IF WE DONT WIN EVERYTHING, SHUT IT DOWN.
It would be absurd to expect Spurs to win the league. What's the point of it even? Just to tell yourself you're striving for the best? If you're not realistic about expectations all you're doing is just lying to yourself. That doesn't really serve a purpose IMO.