Hating people has a lot to do with how people interact with you.
If anytime you go out someone threatns you or rubs their leg onto yours in public transport or whatever the fuck it will be this time, you just default to this mindset.
Has something to do with self preservation.
People who don't have this constantly reinforced may be able to ignore it but it is not really a choice for all of us.
Maybe she just hates pizza to a degree that she wanted to insult the very concept of it.
We will never know.