(The subject box isn't long enough for the title I intended to use; I intended to end it with "when you were younger.")
For me, what I desperately wish I'd learned was how to behave like, and feel like, an actual member of a group. I still don't think I have this down, despite having spent time in heavily HG+ social circles as an adult.
Feeling separate from the rest of humanity is also a Complex PTSD thing, and my abuse certainly couldn't have helped this any; but my parents also raised me to believe that because of my Super Special Way Out There Giftedness, I was something very different from/intellectually superior to anyone I was ever going to meet, or anyone in the world aside from TV child prodigies/geniuses, and I have to say that contributed a lot to this.
I recently found some old records saying that I'd apparently been assessed in the 180s per SBLM. I have no recollection of being assessed, but a lot of my childhood is lost to dissociative amnesia; but it makes sense given what educational opportunities my parents chose for me at various ages, and given how I seem to match up to other people I've known who have been assessed.
My parents never used the term PG with me; they did give me a book about being gifted when I was maybe 8, but it didn't really seem less babyish than most other things aimed at children, and I didn't really get what it was supposed to mean. I didn't link it up with the fact that I was accelerated or didn't fit in with other children. This was probably in part due to my dissociativity (dissociation is all about not putting the pieces together), but the book was also just written in a very vague way and only talked about common experiences for presumed-MG kids in public school. I really wish that as a child, I'd had a name for my difference that made sense, and an idea that there were other real people in the world like me, and maybe even the chance to meet them. (I was an outlier in my family.)
I really wish there was a greater understanding that giftedness doesn't mean what most people think it means. There's a lot of romanticism around the idea, especially the idea of being PG, and I don't think that benefits anyone aside from people whose narcissism is fueled by it. We're all just people.
