surpass her friends (who are either extremely talented or celebrities)
All her friends are either extremely talented or celebrities? This has me extremely suspicious that your friend is not telling you the truth. My ultimate advice to you is to proceed with caution. Be skeptical and if something doesn’t feel right, stop.
To give practical advice beyond what I already said, I’d tell your friend to start her quest to be the best in the world by working to be the best at a couple of things. It’s a lofty (if not impossible) goal to be the best at everything and by focusing her energy at a a smaller selection of things (hopefully stuff she enjoys), she can still find some success.
Good luck.
Even more red flags from my perspective. I know these kinds of statements make it hard to cut ties with a person, but just be mindful the effect they are having on your life and your relationships with others.
I had a similar situation with an online friend in the past and found all their drama very stressful and isolating.