Indeed politics is a very dirty game. When People have a vision, they want to act on it. They want to use politics as a platform to reach out to People but unfortunately it isn't as easy as it seems. You might start to get ahead but along the line, there will always be bad eggs. People in the system who will try to stop you because you are interfering with their personal interest.
It then becomes like a game of chess. They will conspire, lie, dig up your past and do all sorts to cross you. At this stage, some people may get tensed and desperate. They'll want to do anything to cover their back and so they involve themselves in all sorts of defence from bribery, assassination, kidnap etc.
The aim becomes defeated, vision becomes secondary and it is all a game of who will emerge victor at the expense of the people. Only few make it through in good faith .