Political parties (stripping away all else) are groups of people who identify with one another. Take that one step further, and they're groups of people that identify with one another and believe their group is the best one to represent the whole.
Or, if you are less idealistic, they want to win (I subscribe to the idea that they want to win because they think their way is the best way and they like the power).
Once you believe those few things, it's easy to understand why politicians aren't evil, they're just vested in their group; in the same way you'd be vested in your group of friends vs. some random sampling of people you met on the street.
Does this make our current set of political problems insurmountable? No; we just have to mold the system so that no one party can have absolute control even if they control the central government. Maybe by delegating a small set of powers to the central government and keeping most governing done at the local level. Maybe we could call it a constitutional republic?