Yeah, budget & the pandemic screwed up a lot of things. I'm just old enough to be content with what I can get, instead of getting worked up over what might have been.
Yeah, I can't see Asgardian royalty attending high school.
It's strongly suggested, by the way, that Frigga taught Loki more or less in secret, because she saw that he wasn't the jock type.
As for learning how to do magic on one's own... I think it would be plausible that a dedicated scholar could track down some real spell books and learn a few tricks. Not Master-level, certainly, but enough to get out of a jam. After all, where do you think all that magical knowledge
came from?
Somebody did the research.
Somebody wrote those books. And over time, as adepts studied, together & separately, people with greater skills & power arose.
Now, I would agree that Strange was not
philosophically inclined to seek out magical knowledge... until his accident, science worked great for him, and he literally had to have magic shoved in his face before he believed it. But if someone was exposed to magic at the right age, and underwent an ordeal that made it a reasonable solution for their problems? They might just go looking in old bookstores & libraries for answers.
They might even
find answers.