Why is the Mad hatter bipolar? when i watch the movie he seemed to be bipolar. i was wondering why he was like that during parts in the movie?

The name Mad Hatter is inspired द्वारा the old phrase "mad as a hatter." The origins of that phrase dates back to when mercury was originally used in the process of curing pelts in some hats. Carroll and बर्टन both wanted to portray that through the character.