Very true. Also, a surprise for me has been the degree to which it's become clear that even more is mysterious than I realized when I was a teenager. When applying to universities, of course I knew about the initial empirical shocks that founded quantum theory but, for instance, I wasn't aware of the extent to which astronomers were already faced with enough puzzles to make dark matter widely accepted.

There's indeed lots of great instructional material appearing online, which is great. In say, the 1970s, books were often great for self-study but, by the turn of century, they'd all become intended to accompany American undergraduate courses so, e.g., they'd have practice questions with hard-to-get answers, and honestly it felt to me like their median instrinsic didactic quality declined, only the handwavier popular-market ones remained decent, so it's good that more real instruction is appearing again.

I might still prefer book to video but, at least with maths, the stuff even up to the 1970s is already a rather high fraction of what I don't know but would need to, and I have some nice maths books that might keep me happily busy in the hypothetical retirement I've barely saved for.