I think the evil snowman is an analogy of a kind of person.
An unhappy person who is surrounded by happiness.
Maybe he can’t find someone to relate to.
Someone who can understand him.
As the result, he becomes bitter.
Slowly, that bitterness piles up.
And eventually, metamorphoses into hate.
Hate for society who will never accept him.
But, in the end,
I think the truth about such person is that…
The one whom he hates the most…
For his inability…
To be happy.