I wanted to be great programmer, i put in many hours but never became great tho i made better money then friends who i considered great and became a tech executive instead.
I wanted to become a good chess player but failed here too.
Someone suggested 23andme DNA test. After i figured out I've genetic potential of absolute pitch, I've managed to teach myself name of the notes i hear. It took just 10 hours of practise to master this.
I always recognized them but did not have name for them.
Second, i found I've high twitch muscle fibers, which are goood for mass - So i immediately joined gym and made good progress. It's still work in progress but i can see the size difference.
Your friend should list the things they really enjoy doing and try to find the one that has a reasonable tradeoff between fun and future income.
Give that a crack