May be I can explain.
Have you ever got excited over a novel? a film? a comic?
Now imagine that the heroes in your novel/film/comic are real people and they may (and in fact more often than not they do) fail.
The can’t usually destroy the Death Star, the Nazgul regularly take away the ring before it leaves the Shire, the Enterprise gets destroyed by the Klingons at least once a month…
And then, one blessed day everything works as if it actually was a book, a novel, a comic.
How can you be otherwise than giddy with joy?.
See my discombobulated post on the immortal 18th of December of 2022 for an example of a fan trying to express the same sentiment while being carried by the waves of emotion:
The secret, of course, is to suspend disbelief and convince yourself that the sport team winning actually matters, in the same way that you convince yourself that Luke destroying the Death Star matters.