People advocate redistributive justice for a couple reasons.
One, some people are ignorant. They believe it's impractical for wealth to be concentrated in the hands of the few, and forget that capitalism is what built Western Civilization since the 1600s, and that free trade advanced the world since WW2.
Two, some people are brainwashed. Politicians will say what they want in order to get elected, and they intimidate voters into believing that capitalists don't know how hard it is for workers who struggle on a day to day basis. Also, politicians build their careers by spending other people's wealth. In order to become powerful, they need the authority to take wealth away from others who earned it.
However, the most dangerous reason is how many people are manipulative. They believe that life is a freeforall, and that there's nothing wrong with lying, cheating, and stealing in order to get what they want. They don't appreciate how society depends on freedom of assembly so people can choose how to live their lives. Instead, they appeal to emotion in order to rile up the mob. Many people aren't confident with themselves, and only feel good about themselves when living on top of others, and forcing others to do what they want.
Also, many people don't want to be held responsible for their actions. They instantly think it's crazy to downsize government and expect people to live within their means. Instead, they think society is irrational, and the best thing we can do is institutionalize people into social safety nets and catch them after they get hurt.
The bottomline is people who advocate redistribution don't want to think for themselves. They want the government to think for them, and want to punish independent thinkers for being arrogant in trying to overcome the state of nature where might makes right.
