I've been intrigued by the psychology of fans for a long time. You would be an interesting case study. I'm not qualified to do an armchair analysis, but you exhibit some behaviors that I've read about. You aren't unusual - almost all fans have some head-scratching attitudes, beliefs, and behaviors. Thus, the term "fanatics".
A lot of it is based in tribalism. We see it in politics, sports rivalries, different cultures, adjacent communities, etc. Based on the distinctions, those who are X are good, but those who are Y are bad - no redeeming value whatsoever, proving that X is superior to Y. Anything that one hears that Y is bad is accepted without skepticism. Anything good about Y is ignored. Tribalism violates the adage that people are pretty much the same, no matter where you go.
Fans of successful sports teams naturally take pride in that success and really enjoy it. But those who are on the losing end of that success will seek to discredit it in a variety of ways: cheating, favoritism, referee corruption and bias, etc. The pride the successful team's fans take can easily be declared as arrogance, entitlement, etc. And sometimes that is exactly what it is. But the bias of the person alleging that disqualifies them from being a credible judge in making that determination. Lol.
There is also this thing about how sick everyone gets when one team/franchise wins what is perceived as "more than their fair share". It turns into a very strong version of "sports hate" with the bile and hard negative emotions of real hatred. We see it with the NYY, Duke basketball, etc. I'm not much of an NFL fan, but my favorite day of the NFL calendar is when the NE Pats and the Pittsburgh Steelers are eliminated from Super Bowl contention. Lol.
Hiland may be that team in the IVC. While they have won the 3 state championships in boys hoops, there have been plenty of other teams win or share IVC titles over the past 20-30 years. So, if they are that "more than their fair share" school, it would have to be state appearances plus what the girls basketball program has done. They have won or shared 29 straight IVC championships. I can see people growing very tired of that.
I'm a Hiland fan, plus an IVC fan. I take a lot of pleasure in seeing any IVC or local school do well. I wasn't always like that, but I think I met a bunch of really neat people from other schools and decided the tribalism stuff was silly.
Not sure I see a lot of posters "dogging" Hiland fans other than you. But, you do you.