Two words: Spaced repetition, it feels like magic. You are likely going to forget most of what you learn if you don't engage with it and/or it doesn't get repeated.
r/fatfire - same thing as above but for people looking to
have more than "just enough" to retire (multimillion, mostly full of high earners like SWE's, agents or successful entrepreneurs where this goal is somewhat realistic).
r/personalfinance & r/ukpersonalfinance - well rounded finance forum.
r/frugal - okayish for if you are in a really tough spot. If you are doing ok I generally don't recommend them because ultimately you are trading your time/health using most of the hacks from here.
Same, entered college at 14. My social skills were wack, was terrible at public speaking, very socially awkward. Was in my room playing Dota 2 for the first 2 years. I'm just finished up at 19 and I feel more mature and understand why so many universities didn't want to accept me at my age.
However, I think it all worked out, as long as parents make provisions for social adjustment things can work out okay. I don't know about 9 though, seems tough, i literally could not imagine it because college was a lot more than just studying. Especially since I was in a cognitive science not like a hard STEM, lots of social interaction and open ended questions.