Turns out these people identify with the teams and feel a victory as if it was their own.

to be fair, they make financial contributions to the club via merch, ticket sales, etc, which in turn impacts the success a team can achieve by spending that money

I once talked with my date about football and she said, well, when there is a really big game, she likes to watch, otherwise not really. And i asked why, it's the same game. And she said, she doesn't really know, she just likes to cheer for a team and hopes that they win. Which i found interesting. It's like gambling, but boring and stretched out. When i was younger and people asked me what my team was, i always asked which team is the best, or winning, and that was my answer. Then you get so much shit for being a bandwagon fan. Like dude, you are cheering for a team that has been losing for 10 years like your life depends on it, get a grip.