Excellent accounting of what being a fan means to YOU.
You rightfully expect that you are free to be a fan in the way that suits you. The disconnect comes when you start criticizing "some fans" for being the version of a fan that suits THEM. You expect that you should be able to fan in the way that suits you, but actively condemn and criticize "some fans" for fanning in the way that suits them. For some reason you and a handful of others seem to take it personally when someone takes what can appear to be a negative outlook, then you lash out with a passive aggressive comment seemingly intended to exhibit your superiority as a fan. It's not the end of the world that others have a different opinion.
Just because a fan forms a negative opinion based on the realities they have witnessed over decades, doesn't mean they go into watching a game in a state of "gloom and doom", or "depression". This seems to be another common denominator among the need to be positive crowd. You/they assume the worst possible emotional state of the antagonist and use it against them as if it were a fact.
As far as the team goes. There are some foundational aspects of this team that have consistently failed over an extended period. The result of that is some fans are very likely going to recognize the pattern and adopt an attitude that leans more towards 'show me' than hopeful. There is nothing wrong with that and it seems the prudent thing to do.
When you start making it about the poster and not the post you are getting way out over your skis and that almost always ends up in a 'yard sale'.