Either they treat their fans like effing shit and their fans love it, because Nintendo left Sega in the dustbin of history decades ago and has yet another hit console right now, or you are full of shit.
I'm going with the latter.
This has nothing to do with how Nintendo consoles have been selling.
Tell me one instance where Nintendo has listened to fan suggestions or fan works/projects that doesn't involve hard backlash from everyone after an initial showcase.
You obviously haven't followed gaming news the past years, because there has been nothing but controversy surrounding Nintendo and it's legal fore-front which does nothing but affect fandom as a whole.
You can't even make a drawing of Nintendo characters without being C&D/DMCA'd by them on the spot.
Not even mention how they have been putting a halt on everything that has any kind of connection to their IPs.
Compare that to how Sega treats their fandom with fan projects and other media.
A whole different world, almost the entire opposite if I'm being honest.
Sega's relationship with their fandom is one of the best I've seen in all media, and compared to Nintendo's, that's just an insult.
Even worse, Nintendo didn't even bother to address the Jo-Con drift situation until they were close to being sued by a US law firm.
If that doesn't speak leagues about how Nintendo gives the finger to their fans while they simply fill their pockets without caring about them, then I don't know what does.
Nintendo doesn't even listen to fan feedback in the slightest unless they are hit with backlash hard from all around the world.