Most seem to have more passion for football — and will often spend money going to a good away game and bowl games. Since more money is being spent on football, we don't have the same money as Gonzaga fans, where basketball is THE sport.
Of course, if we had a few years of top 25 basketball teams (or even NCAA tourney teams) and the football team keeps having 6-6 or even 7-5 seasons, you'd probably see more fans willing to put basketball first. Part of the issue now is basketball has not been doing that much better than football.