Everyone is tribalistic. People biasedly support their family, friends, local community, sports team, alma mater, country, etc. over groups they don't identify with.
What I find insane is choosing to place precedence of country above all so highly that you'd support an athlete from the opposing school (who has trash talked / disparaged your school and who for every other sporting competition you cheer against) over a Hawkeye who isn't American.
I don't follow the logic of that tribalism precedence hierarchy.