Of my close friends that are Ute fans, I'd dare say 70% of them grew up BYU fans, easily. Many of the "biggest" Ute friends of mine were cheering for BYU late into their teenage years and in some cases early adulthood.
What tipped the scale for them was 2004 which was then cemented by 2008 and their PAC 12 entrance. Basically their fanbase received a huge surge similarly to the way BYU obtained a huge following in the 80's and early 90's.
Unfortunately BYU hasn't countered by having a "special season" for the young generation of young Utahns to have reason to jump on the BYU bandwagon. Most of Utah's youth have never witnessed anything remarkable with BYU football in their lifetime, in fact many of Utah's youth were too young to remember the last time BYU beat Utah.
For those of us living in Utah we can all testify just how the Utes have taken over. I expect that in Salt Lake and Tooele County but unfortunately they have spread into southern Salt Lake county, Davis County, Washington county and unfortunately Utah county. All historically rich BYU dominated areas.
It's been extremely frustrating to watch it unfold. My two oldest sons where their BYU gear to school proudly however. As for me and my family, I will never cheer for the Utes.