Is it because the brain or cerebellum is underdeveloped that you will feel dizzy when playing 3D FPS games?

Personally, I think it's not the brain and cerebellum, but the player's physique. Generally, people with good constitution will get used to it. Players with poor physical fitness who play night markets (online games all night) may be worse, dizzy and vomiting. I suggest you have a good rest and don't indulge in the internet! ! !