In a book like Peak, are there examples of those who have spent years (starting from childhood) in deliberate, proper practice who have not become “experts”? The kid who is a basketball whiz in middle school, but stops growing at 5’8" may be a very good basketball player, an expert perhaps among his peers, but is highly unlikely to become an NBA star because he is just not big enough. The same player at 6’8" in all likelihood would be a star.
Absolutely, focused practice/study can get one very far, but if someone has no or very little talent, the chances are not good that they will pursue that area long enough to get to the expert level. Thus, there are no good control cases for research like that done in Peak (I haven’t read the book, so just based on website reviews and summaries).
Also, as others have said elsewhere, there are countless athletes, musicians, singers and actors that have been well-trained, properly practice etc. but do not have the “spark” or “it” factor that makes them a star. They may well be an expert and do well in regional theater/orchestras or lower level sports leagues, but will never make it to the top. What is the difference between Michael Jordan, Steph Curry or Lebron James and other guys that make it to the NBA? Is it really their level of appropriate practice or is it exceptional talent, along with practice?
Academics are a bit different. I think there are very few areas of study where a person with average to above average intelligence could not become an expert, with a lot of work, the right course of study and appropriate mentoring. The message that working hard will allow a student to excel is really an important one and students, especially those that make it to a top college (assuming this was on their own merits and not due to an excessive amount of HS tutoring or some special status), have the ability to study whatever they want, as long as they are willing to do the work.