imho the point of leftism is "power to the people". It's about fundamentally believing that there's something valuable in the collective sum of people worth voting, fighting or arguing for.
It might require a vanguard, but at the end of the day it's to promote the interests of the masses (whether or not you agree we actually have that in our hearts/can actually compute/calculate this, etc)...but it's to oppose the church, the hereditary monarchy pretenders, the aristocracy, and if necessary the state.
It's not purely about spite...but we do plenty of things out of spite.