Amazing isn't it? The delusion is so strong, it's like you've stepped into an alternate reality.
But what's really worrying and scary is that because they live in a self deluded bubble they only hear the same voices saying the same things, so they believe it. Deep down they know it's not true, but they can't accept it so they believe crap like this and as they don't hear any dissenting voices from their side they eventually convince themselves it's true. Facts don't matter, just keep shouting your delusion because you know the majority on your side will back your story because they want to believe it rather than accept the truth. As the only ones saying anything to the opposite are fans from other clubs, it's then easy for them to stretch the delusion further and say it's the "cartel" or the "establishment" that are against them, reinforcing their delusional behaviour.
The herd moves in one direction with one voice. It doesn't matter if it's the wrong direction. Anyone in the herd saying something that doesn't conform to the accepted view is drowned or forced out. Safety in numbers and ignorance is bliss. No time for introspection or accepting mistakes or dealing with uncomfortable truths. Just ignore the bits you don't like. Few in the herd will speak out because they all want to belong, they all want to be seen as the most passionate, they want the glory of belonging. Anyone bringing facts, truths, or dares challenge the orthodoxy of magpie superiority is the enemy, anyone who dares to leave is a traitor. The outsider undermining them, the "establishment" holding them back, the "cartel" cheating them from their rightful place at the top and winning trophies, jealous because of their passion and the magnificence of the magpie horde that should be admired and loved by all. Just like Stalinist Russia, China under Mao, Nazi Germany under Hitler, the mags are a cult where it's easier to believe the narrative because so few of your own challenge it than to accept that in reality you're not that big, not that successful, not that popular, not that good and that there's bigger, better, more successful and more popular out there.