I struggled a good deal of my life with thinking I'm mentally challenged. IQ tests of various types have all proven the opposite, but I didn't think that meant anything. Of course I'm not mentally challenged, but it took a while to convince me of that.

I agree that stupid people don't realize they're stupid.

And by the way, making mistakes and not knowing something are not what makes a person stupid. Everybody makes mistakes. Everybody has things they don't know. Is everybody stupid? I don't think so.

In my case, I have PTSD from child abuse, neglect, and school bullying. Years of it. My mind has been so preoccupied with healing from what I've been through that if I got spacey and scatterbrained, wouldn't that be understandable? I simply didn't have room for more information until I could clean all the emotional garbage out. If I didn't know how to do some major life skill (I was 48 before I got my driver's license) isn't that because nobody wanted to take the time to teach me, even though I asked them to? Whose fault would that be?