Okay but not gonna lie, I rarely see anyone who likes Shu is sane. Those who are, thank you very much.
But, seriously. I get it, Shu is popular but that doesn't mean his fandom has to be super toxic and weird!
Most Shu fangirls I come across turn out to act somewhat mentally unstable, and saying shit like "I AM MARRIED TO SHU KURENAI" and "STAY AWAY FROM SHU OR ELSE ILL KILL YOU WITH MY KNIFE." That's so stupid and you can tell these are literally kindergarteners or preteens. They know nothing of love except spending all their energy on a fictional character.
These crazy people also become angry when another person likes the same character, even in the most non-romantic way popular. They lash out at others and whatnot. Also, that Shu Fanbase has a fucking adult crushing on him, too! What the hell?
ALSO THE IDIOTIC FANFICS? Come on, barely do I see an OC x Shu fanfic by a fangirl that is actually really good. Most of the fanfics are just about OC meeting Shu, and then falling in love. There's no actual and original plot whatsoever. Then the story gets reads for some reason, despite the obvious lack of interesting plot... as well as obvious shit like bad grammar and lack of characterization.
People also make Shu freaking 2D. The fangirls — for their own enjoyment — write Shu as not the complex and chill character he is, but make him flirty and that's it. They write him as paying attention to his girlfriend all the time and lovey-dovey. They seemingly forget that his friendship with Valt is what drives his characterization the most, as well his ambition to become stronger.
THEY LITERALLY MURDERED SHU'S CHARACTER BECAUSE THEY LOVE HIM SO MUCH.
Anyway, that's it. Other characters in Beyblade Burst have a somewhat tamer and more mature fanbase compared to Shu's. Shu is not necessarily a bad character himself, but his fans are really whack and most of them don't have a shred of common sense.
Speaking of which, which is why I sometimes make Shu the butt-monkey in my works. In no way do I like writing bashfics for characters, but I do like writing stories that screw up one's perspective of him (hence my horror stories, etc.) and "ruin Shu" for people (even for me!). Either way, I just like screwing with people's perspectives by default.