When I grew up a Utah fan, pretty much every Utah fan I knew was also a friendly active member of the church. That's not all of them, but it's what I saw.
When I was at BYU, most students I saw and I interacted with were fairly liberal. It's not that everyone at BYU is/was...but that's who I was around.
My sister-in-law in Utah was convinced Biden would win Utah over Trump in 2020....because the people around her supported Biden and there was a groundswell of support that she saw.
Looking at the big picture is often very different than looking at the people we self-select to associate with, many of whom mirror our own inclinations.
So if you're a Utah fan who is the type to speak out against someone smashing headlights on a BYU car? Then you're probably not the type of person around the fans who ARE doing it, so it doesn't seem real to you