It's to gain an identity in society, to have a common opinion with other folks. Some people take it way too serious, we have the idiotic conservatives in the south and we have the idiotic liberals in California.
I think this is a good point too. Politics is the last place in Earth where people should group up and hivemind just because they want to be a part of something, yet politics is where this happens the most. That's why I think more or less, the idea of democracy at its very core is ineffective, dumb, etc. Not just that, but the concept is a bit of a lie all in itself - it's purely built on the idea of giving people the illusion of choice, and making people feel they have an important opinion. The reality is that government decisions are made by elite groups, and those elite groups have been and always will remain the same families and groups of higher-classed citizens. Society is too busy being at odds with itself to make any sort of meaningful progress. We have people pushing political decisions based on scripture written thousands of years ago, and not just the minority, but a majority. It's one big giant shit-show.