No, politics is not bullshit. Yes, many but not all politicians, appear to be concerned primarily with their own interests rather than those of the people they purportedly represent.

The dominance of political parties is a signfiicant factor in that for without party support it is difficult today to get elected at all and once elected, if a politician does not follow the party line, then they are unlikely to be re-endorsed.

However, it is rarely, if ever, sensible to generalise in such a way for there will always be exceptions, though I agree it can be hard to find or to recognise them among politicians.