I was a die hard Cub fan raised in Chicago. Moved away many years ago. I am an ex-Cub fan because being a sports gambler, I'm an ex-anybody fan and am only a fan of whatever team my money rides on. Thus I can root for my hometown. [As long as my money is on them as it properly was.]
Very simple logic to me. Just don't understand sports gamblers being fans. Another reason why most lose.