In Rudolph the Red nosed reindeer, why were the reindeers mean to Rudolph?

Because he's Rudolph the RED NOSED Reindeer

The other reindeer considered him a freak because he had a glowing red nose.

He's a freak show in the eyes of the reindeers.

Because he had a red nose, which was different from their noses.

Because of the red nose. They were bullies.

He was different, that red nose thing that he had going on.

He was different from the rest of them

his nose looks like a huge tomato that lights up.

Because he's a mutant; with an undesirable trait which they do not wish to perpetuate further within the species.

because hes a freak raindeer