Ah, well, so as you know we live in an exploitative capitalist hellscape where our humanity is ground down until we're depressed cogs in a machine that doesn't even produce profit efficiently but which makes those that own the machine feel good because they have so many people under their control. But if you discuss this in public then those that own the machine or the sycophants who want to win their favor to end up in a better position in the machine get mad at you, so most people have resigned themselves to spending most of their lives being a cog in the machine.

This results in two emotional dynamics. Firstly, people are afraid of angering the sycophants of the machine. Secondly, people want to keep some parts of themselves safe from the scouring force of the machine that seeks to make them smoother-running cogs.

The first is mostly important when discussing pay in a like-for-like situation. If you discuss your pay with coworkers in the same company or the same job title, that undermines the power of the employer, so the employer wants to find ways to punish that. That sort of punishment is illegal in many jurisdictions, but it's hard to enforce and hard to prove, so effectively employers can get away with a lot of punishment. This means that employees that fear that punishment will avoid discussing pay and get mad at you if you do, which would risk implicating them.

The second is more relevant when it comes with the situation with your friend. Exam results are a feedback mechanism to turn you into a cog in the machine. You learn to think in the way they want their cogs to think, and people that learn to think that way most efficiently get put in positions where their thinking perpetuates the system of oppression. And like any good feedback mechanism, they are enforced with rewards and punishments and the promise of more rewards for continued loyalty.

People who struggle at tests are expected to sacrifice their humanity to score better. To give up social development, physical fitness, joy, friendships, exploration, curiosity, time with family and love to work for a system that will grind their souls into dust if they let it. Yet every system and most adults in their environment tell them this is the right choice, and there are usually-false promises of financial security and a roof over your head and respite if only you work a little harder for the next little while. This makes it all so tempting to ignore your own boundaries.

Most people give in to the system partially, becoming cogs for most of their lives, but they still know what is being taken from them and they still try to hold on to what humanity they can. They carry that resentment even if they never consciously thought about the structural issues that produced it or the greater political context. And then you come in with your better grade, proudly announcing that you're the physical embodiment of what the system blames them for not being. So of course they feel envy and resentment towards you, because in that moment you're doing what the system wants you to do to scrape away a little more of their humanity.

And this same logic of resentment applies to comparing pay in an unlike situation.

This means that if you want your relationship with your friends to be healthy, beneficial, and enjoyable for the both of you, you only talk about pay or grades in a carefully established emotionally and socially safe zone that mitigates much of the harm that would occur if you just talked about it when it seems relevant.

Neurotypicals of course communicate most of this through emotional subtext. A neurotypical who says "You should never discuss grades with anyone" means that you need such a safe zone. They might establish such a safe zone through a display of shame and vulnerability and seeing whether their conversational partner fulfills their part in the social ritual by making assurances and offering warm support. Even without the neurotypical subtext display, creating a safe zone is necessary, though; everyone has feelings and mental schemas.