Since you don't seem to be aware of it, one thing "bro" strongly and literally implies is Frat Culture. They literally call each other "brothers".

In case English isn't your native language, or you're lucky enough to not be familiar with this dark side of American culture, the commonly used terms are "Fraternity Brothers", "Frat Brothers", and "Frat Bros", who become "Tech Bros" when they graduate.

And YES, it is a culture, and a notoriously toxic pervasive culture at that, which Snapchat and Uber exemplify.

https://www.theatlantic.com/technology/archive/2014/05/snapc...

>Snapchat, the App Frat Bros Love, Was Started By the Frattiest Bro of Them All

>Evan Spiegel, the CEO and cofounder of Snapchat, has created a massive, popular application. It's basically a frat boys dream, and as it turns out, Spiegel was the ultimate frat guy during his time at Standford.

https://techcrunch.com/2014/05/28/confirmed-snapchats-evan-s...

>Confirmed: Snapchat’s Evan Spiegel Is Kind Of An Ass

>I’ve known Evan Spiegel, Snapchat CEO and co-founder, for a while now. We have had more than half a dozen in-person conversations, far more phone calls, and even shared twenty minutes together on stage at Disrupt SF. And try as I might, I’ve had a hard time liking him. Now, after reading emails sent by Evan Spiegel during his undergrad time at Stanford, I clearly understand what my instincts were telling me.

>Dude’s kind of a dick.

>You can see the whole swath of leaked emails at ValleyWag, but I can summarize them all pretty easily for you with the above paragraph. Here’s a typical example:

>“LUAU FUCKING RAGED. Thanks to all of you. Hope at least six girl [sic] sucked your dicks last night. Cuz that didn’t happen for me.” Signed affectionately, “fuckbitchesgetleid. Spiegel.”

https://vator.tv/news/2014-05-28-snapchat-ceo-emails-talk-ab...

>Snapchat CEO emails talk about "bitches" and "sluts"

>Emails from Snapchat CEO Evan Spiegel reveal gross fratboy misogyny in the wake of UCSB shootings

>Breaking news: rich, white man says awful things. Other white men rally to his defense.

https://www.huckmag.com/art-and-culture/photography-2/americ...

>Inside the dark, depraved world of US frat culture.
American ultra.

>Photographer Andrew Moisey explores the rituals, texts and initiations of American fraternities: breeding grounds for aggressive, toxic masculinity.

>The world of American fraternities is a strange and ghoulish one. Depraved and simmering with violence, it’s a hotbed of ultra-masculine entitlement: a grim embodiment of chest-pumping male tribalism.

https://www.theguardian.com/artanddesign/2018/dec/10/andrew-...

>Humiliation, homoeroticism and animal cruelty: inside the frathouse

>Photographer Andrew Moisey uncovered ritual hazing, extreme drunkenness and toxic masculinity on one college campus – from men destined to be America’s future leaders

>[...] A world in which homosexuality is taboo but cross-dressing and semi-naked wrestling are acceptable and parading your penis and testicles is almost de rigueur.

>[...] “These all-male campus spaces have been around since the 1820s,” elaborates Moisey, “but they changed perceptibly during the so-called culture wars of the 1970s, becoming a safe space for guys who didn’t want to have to worry about having their kind of fun.” Many fraternities, he believes, now view themselves as embattled institutions, maintaining their conservative core values of brotherhood, privilege and machismo against a perceived liberal onslaught. Disturbingly, the code of loyalty to the brotherhood endures even after the other principles of fraternity life have long since fallen away.

>“The central issue is that there is an allegiance to everyone inside the fraternity rather than to the higher ideal,” says Moisey. “So even though most of these guys consider themselves highly respectable, their loyalty is such that they will protect the bad guys who hide in their midst. If you are a bad seed and you join a fraternity, you have found your safe haven. And what we are seeing right now is that the support and protection that fraternities provide for the bad seeds extends into the highest echelons of American power and decision-making.”

>[...] “This is what our leaders looked like when they were young.”

https://www.andrewmoisey.com/the-american-fraternity.html

>ANDREW MOISEY: THE AMERICAN FRATERNITY

>An Illustrated Ritual Manual