Oppression does have benefits sadly, thats why people do it.
Its like when people make the argument ‘torture doesn’t work’. Yes, torture does work. Thats why its so common. Maybe it doesn’t work for intelligence gathering, but it does work great as a deterrent, which is its main function.
Being a member of an in-group has benefits. Politicians listen to your problems more. Police are more respectful. Jobs are easier to get and pay better (you’re the first hired and last fired). Mating is easier in many ways.
Take Mississippi in the 1910s. White men made up 30% of the state. White women were 30%, black men 20%, black women 20%, more or less.
Virtually all positions of importance were held by white men. So you made up 30% of the state but held 95% of all important positions in the public and private sector. It was much easier to find a middle class job in Mississippi as a white man than as a white woman or black person.
Also white men could have sex with both white women and black women. Black men could only have sex with black women. 60% of men had access to 100% of the women.
Politicians didn’t care what women or black people wanted since they couldn’t vote, but they cared deeply what white men wanted.
Sadly there are benefits to oppression for the in-group in charge. Thats why it happens so much. Life is a struggle for survival, and the oppressive group tends to have better access to resources, status and mates.
Other animals break up into social hierarchies too. Chickens, other primates, wolves, etc.
Sadly social dominance hierarchies are built into our DNA. Its our job as thinking apes to develop social systems that can tamp down these urges and create a more egalitarian society.
Making sure the oppressed are represented in the political and economic systems is a huge part of overcoming this. Oppressed groups need political capital, human capital, social capital, financial capital, etc. to fight for justice.