Because you don’t understand the nuance of the Bay Area. There are rich and poor places on both sides of the Bay, but in general, SF is wealthier and the peninsula where candlestick was has a shit ton of money. Oakland was more known as a large suburban city riddled with violent crime and gangs and the surrounding smaller suburbs like San Leandro and Hayward the same. So you could live 20-30 miles further east in the more conventional suburb and be a Raider fan and your neighbor in the same neighborhood a Niner fan and that Niner fan would think they were better than you simply because of the team they rooted for. It was obvious and it was made obvious by Niner fans. Shit rubbed us wrong. Then, you throw in their success and gloating and it just made you hate that team. I still hate them. I love watching them be so good but an able to finish the deal. It’s cathartic.

It’s probably very similar to how White Sox fans feel toward Cubs fans.