If you refer to a young person as a whiz-kid, you mean that they have achieved success at a young age because they are very clever and very good at something, especially making money.
[informal]
...a computer whiz-kid.
...a whiz-kid physics student.
whiz kid in American English
Slang
an exceptionally talented and comparatively young person, esp. a newcomer, who shows great promise in a particular field