Isn't investing into a team the result of being a fan, not the reason for being a fan? Speaking for myself, I invest my time and money into following BYU football because I care about the team and the school, not the other way around. I care about both because they represent my alma mater and the church and don't apologize for it. Win or lose, the reason I care about the team doesn't change.
I want to get a good return on my investment too, but that can mean a lot of things. For a lot of people it's seeing a good product on the field and getting wins. That's important to everyone, but I also think you have to consider other aspects of investing. Just like financial investments, there's risk. You can't expect your stock in a certain company to guarantee a high rate of return immediately after a new CEO is hired. And you also can't panic the moment the market shifts. Good investments yield long term net gains, which I think BYU Football has brought to most fans, despite some mediocre seasons of late.