Explain Like I'm Five

Your brother is on a (specifically designed and heavily funded) pipeline to being a total piece of shit (not just with misogyny, but racism, and probably queerphobia and ableism too), do what you can to get him off it. A quick search brings up what looks to be some good info to start you off:

Manosphere

Misogynistic influencers are trending right now. Defusing their message is a complex task

De-radicalising incels out of the ‘manosphere’ through Reddit

Making a Radical Misogynist: How Online Social Engagement with the Manosphere Influences Traits of Radicalization

Swallowing and spitting out the red pill: young men, vulnerability, and radicalization pathways in the manosphere

Exiting the Manosphere

There are also many youtube videos on the subject, though I haven't watched any recently, so I won't link, but look up something along the lines of "manosphere right wing pipeline" and you should see some results.

Just tell him that alpha and beta thing does not exist in the wild. Even the author said so.

https://phys.org/news/2021-04-wolf-dont-alpha-males-females.html

It does not apply to humans. Are you saying your brother is a wolf? Is he a furry perhaps?

Humans are more complex than that.

"Alpha male" basically translates to toxic masculinity, and "beta male" basically translates to anyone who respects other people in any way. It's the callsign of pieces of shit like Andrew Tate, who is a human trafficker and serial sexual abuser currently in prison awaiting trial in... I think it was Croatia?

He doesn't know what it means to be cool, so he's hoping that just declaring that he's cool will be good enough to make him popular.

The problem is that the kids who try this strategy almost universally cannot pick up on social cues, otherwise they would understand that it will always lead to the opposite result. People who seriously say out loud that they're alpha males are pretty much exclusively losers or scumbags.

He’s watching toxic YouTubers like Joe Rogan and Andrew Tate.

Tell him calling himself an alpha is just what a beta would do. Real alphas don't say shit about themselves, they have people who do that for them. Watch him implode.

If you want advice on how to handle this: ask questions. Ask them calmly and without any judgment. Be genuinely curious.

"What makes him a 'beta male?'"

"What characteristics do you admire most in 'alpha males?'"

"What characteristics do you think you have?"

"Where'd you learn about all this?"

Don't ask them in rapid fire, pepper a question in here and there over time.

Beat his ass to establish dominance.

Get him off YouTube and social media

You got opportunity here to tame him, ask him what makes one alpha?, then convince him that you are one or at least superior than him. Then, you will unlock ability to demand more share in things like food and money. But he looks like person who just argues.