If you're on the same team and supposed to be working together why does a coworker say the most rude insanely mean spirited crap day after day?

Sounds like where I used to work, had a woman who could say anything negative about anything a person liked or had that she didn't have or whatever. I mentioned one time I saw a rose-printed sofa I really liked and she started in saying how ugly they were. Everyone got silent on that one. Later on she told someone she worked with that every morning at the breakfast table her husband would look at her and tell her she was so ugly he didn't know why he married her. What a hell marriage and she stayed with him.