I don't know your friend, but he may feel like he's losing you as well. The world is burning and cishet men have trouble finding a place to be safe. We assume they don't need one, but most of the space they have is not good.

It's hard to do what I'm going to suggest when you are suffering as well, so put yourself first. Forget any groups, treat you two as your community and ask what exactly is bothering him. What happens that make him feel oppressed? How does you supporting another community harm him? If anything else, his pain is real, he can't put it into words and end up invalidated. That's actually a point you have in common, you may start there.

That doesn’t sound like much of a friend, chief

As a starter, you could ask him:

• How many countries currently have laws making it illegal to be cishet, sometimes punishable by death.
• In the US, how many states have passed laws making cishet relationships illegal. What year were they repealed?
• How long did it take for an American president to openly support cishet marriage?

...but like other folks have talked about, it's difficult to use logic to get someone out of a position that they did not logic themselves into. You're arguing with feelings, and so long as he feels oppressed, that's going to be the truth of his world.

Ask him if anyone will kill him for being straight. Until he's under threat for his life and well-being for simply existing with certain biological characteristics, he's not being oppressed. He's being discriminated against.

There's a difference between being discrimination and true oppression. What your friend feels is discrimination in his exclusion from the LGBTQ+ community.

Discrimination makes people feel bad. Oppression kills people.

Your friend wants a space where he can commiserate about the discrimination he perceives as a straight cishet man. Your community wants a space where they can feel safe from oppression primarily instigated by straight cishet men.

Your friend's presence in that community, without additional context, is a threat. There are far too many stories of straight men gaybaiting the LGBTQ+ community to set them up to be robbed, assaulted, or murdered for anyone in the LGBTQ+ community to implicitly trust them.

The LGBTQ+ community isn't oppressing your friend, but they have good cause to be suspicious of and discriminate against him if they have no other information about him other than his demographic. He's expecting them to express patience for him whining about his life when people from his same demographic are actively trying to harm them.

If he wants sympathy from the LGBTQ+ community, then become an ally and actively work with them to protect those who are being oppressed. This is how you earn your place in a community and their sympathy.

I wouldn't bother tbh. Studies have shown that when people are given facts that contradict their beliefs they just end up doubling down.

Toxic masculinity does play a shitty role in how men are expected to act and behave in society especially in conjunction with how patriarchal our society is.

Would I say it's oppression? Not really, it does push men to be emotionless slabs unable to express themselves properly.

But in my experience cishet people saying that cishet people are oppressed don't mean the toxic pressures of our current society and societal expectations.

Without knowing examples your acquaintance is citing it's basically impossible to have the conversation.

Does our society chew on cishet men? Yes.

Does our society chew on queer folk? Very yes, more so than cishet men as the chewing that it does on cishet men is usually also stacked on queer folk as well.

(I have read your link with additional context)

This stuff is really frustrating, I'm sorry that you're having to deal with this stress. It can feel like we have an obligation to try and talk some sense into people who are on a harmful path, but remember that your first duty to humanity is your duty to look after yourself, to the best of your ability.

The saddest thing is that I do think that cishet men suffer a lot under the patriarchy, and I think that's what can make people like your friend vulnerable to the alt right messaging — they may be aware that they're considered privileged, but without an understanding of systemic oppression means, they interpret that as "they're saying that being a man makes things easy for me. If I'm so privileged, how come I feel so lonely and unfulfilled?". At the core of many of these men is someone who is struggling in some way, and then struggling a bit more because the system we exist in says that they're not allowed to be struggling. My sympathy ends when they internalise the right wing rhetoric though.

The problem with that rhetoric is that it looks at life like it's a zero sum game, where any player gaining "points" does so at the expense of another player's points. They believe that nothing comes for free, and they distrust concepts like altruism, and compassion, because clearly that person is just trying to get a leg up on everyone else. If the idea of systemic oppression is even broached, it becomes a "suffering Olympics", of who has it worse, which is a nonsensical way of looking at things. I'm cis, white and disabled, am I more or less oppressed than a black, cis, able bodied person, or a white, trans person? I don't know, and I don't care, because I do know that each of these people has insights that I don't, so their viewpoint is essential for building an intersectional understanding of oppression, as is mine.

People like your friend often talk as if they are advocating for men's issues, but all they care about is stealing the stage from others. Being cishet is the reason why he's not a part of the LGBTQ community, but it sounds like him being an asshole is contributing to you not wanting him as part of your wider community.

Just pull up the Wikipedia page about LGBTQIA rights, show the anti-trans bills that have passed, the death threats against agencies that show any level of support.

I wouldn't even try to argue that cishet men aren't oppressed because: A. The burden is on the person making the claim, B. You can't prove a negative, and C. It's irrational to think that they are.

I'm a cishet man myself, and while I've experienced a lot of hate for being gay, there has never been a time I've received any hate for being cis. That's just ridiculous.

Echoing the sentiments of everyone else in this thread. I wish you good fortune in discovering an actual friend to replace this loser.

Tell your friend to read a history book or legal precedent. Or, hell, any nonfiction book. I’m 38, so none of this is that long ago. When I was growing up, gay sexual contact was illegal in my state. In some states, when I was a kid, men could not legally rape their wives. (As in, if nonconsensual sex took place in a marriage, it was not considered rape). And I don’t remember any states ever taking cis kids away from their parents because they considered seeking appropriate medical care to be abuse. Has that guy ever feared for his life because of who he was attracted to? Friends of mine have, because they were queer. Ask him how many countries his future marriage to a woman would be illegal in? In how many countries could he be killed just because someone found out he loved a woman? The reality is, algorithms on the most profitable social media sites have been driving young, cishet, mostly white men to the alt-right, homophobic/transphobic/misogynist/dickhead rabbit hole. Your “friend” may or may not be savable, but if he is, that’s the opposing army you’re dealing with. A 24-hour bullshit cycle of the sociocultural preconditions for fascism.

That's just ridiculous. While men do experience unfair discrimination in some areas, in no way does that rise to the level of "oppression and stuff." LGBTQ+ people's experience includes many more discriminations and obstacles and outright dangers.

Althought it's not a contest, people with a much greater need should have their situations remedied with greater haste and attention. Even with that in mind, it's okay to ideally want everyone's troubles to be relieved. You (not you personally, the generic "you") still have to prioritize efforts in practice.

And now he thinks straight people should be included in the lgbt

So I read your link, and it sounds like he wants to be included in LGBTQ? Ask him which letter he wants, and welcome him on in. But do remind him that he can't have the L unless he also embraces the T.

I have seen some data on that matter for the trans case because it's something I investigated recently to rebut the transphobic propaganda in Spanish right-wing media when a pro-trans law was recently approved. But you can also find similar studies for other members of the LGBTQIA+ group in Google Scholar.
There are four times more mental health issues like depression and suicidal ideation among trans people (https://doi.org/10.1016/j.jadohealth.2016.06.012) and twice more suicidal attempts (https://doi.org/10.1542/peds.2019-1183) because of what they have to go through than cis people.