The desire to be a politician is typically a desire to mold society into one’s own ideal vision of what society should be. A vision of society that especially accommodates one’s own desires. It’s another mechanism by which we try to seek security and purpose for ourselves.
Politicians tend to think their ideas are the best and are willing to cheat to see that their ideas win. Even though democracy by its very nature is supposed to be about the rule of the majority. Politicians are usually more than willing to ignore or circumvent the wishes of the majority when they think they can get away with it.
Therefore, it’s not the system they support. It’s not democracy (the will of the people) that they care about. It’s the worship of their own ideas (or the ideas they’ve adopted from others).
People of opposite political opinions often have one major thing in common though: they want justice.
Their sense of justice may sometimes be skewed or misdirected, but generally that’s what they want: justice. They want things to be fair.
The problem is that not everyone agrees on what “fair” actually is. Political motives are almost always fueled by the fear of justice not prevailing (justice as they see it).