undercover baller

A successful and wealthy person who does not flaunt personal achievement to the general public to boost their own ego.

Sarah: Girl, Maxamillion took me away to Bora Bora for the weekend and we lived it up.
Jennifer: Wow! I never would have fathomed that Max was balling like that since he wears old dude New Balance kicks and general contractor trucker hats.

Sarah: I know right! He's an undercover baller!