I hate (some) New Yorkers? Why? because half of them don't support their teams who suck at some times?

I hate some new Yorkers because they say they are the ultimate fan of NY, but they don't support both NY teams. I have friends who love the Yankees and the Giants, but they that the Jets and the Mets "suck" and hate them. WTF? If you were a true fan, you would support all of them, not just the ones that are good. Do you see my point or do you see why?