I've gotta be honest, the few people I've known who've gotten some sort of neurodivergent diagnosis later in life, I think everyone around them was like "yeah we already knew that."

The people around me had a very different reaction.
So I've not been officially diagnosed, but when I was 48 I went to a psychiatrist for my depression and after a few months he told me he thought I had autism. Just out of the blue.
I was a bit shocked to hear that and I thought he must be wrong. So I told my (neurotypical) friends. And they're all like "yeah, we've known that for years"

Yes, and that reaction also fucked me up completely and gave me imposter syndrome about my own diagnoses.

I've found that the sooner I get toxic people out of my life, the sooner I feel better about everything

People like you to fit the mental model they have of you and tend to reject the infomration that doesn't match what they already believe.

Most people view being diagnosed with a condition to be some huge thing that makes the person totally different from a "normal" person. To them, a weird person is just a weird person - significantly less removed from the norm than a full diagnosis. It's the same reason why a lot of people don't want to get diagnosed, because it would make them believe they're "broken."

I haven't actually told anyone, only my wife, that i have auDHD. Others thinking I'm just slightly odd is good enough. Though yeah I'm fairly sure it would go over exactly like the meme says if I'd ever reveal my diagnosis, because many of them do think only the high support needs or level 3 autistics are actually truly autistic, rest are just faking it.

Yes yes yes