Why are all the Charmander fans immature and always find it cool to talk bad about other starters and their fans , even in their 20-30s?

Whenever i go into a pokemon forum or community, one thing is common.

Charmander fans always go glorifying their starter and talk shit about Squirtle and Bulbasaur.

Even yesterday, there was a post in reddit about a 8 years old boy that died and his parents putted a Bulbasaur statue beside his grave.

They didn't respect that and went to go "bulbasaur is stupid, Charmander all the way" "That child is poor to have Bulbasaur lol" and so on.

In youtube, facebook, iFunny, Memecenter, 9Gag they always go like that.

And considering Pokemon R/B/G released 20 years ago, They are like in their 20s or 30s.

What's with their mentality?