In some culture tipping is not the norm, and for others tipping is considered an insult. In most restaurants in Italy service charge is included in your bill and its not customary to tip in Italy. I don't think its fair to apply customs from one country to another, it doesn't matter how rich someone is.
I've been to Rome and when in Rome you tip. Also it is customary for Americans to tip everywhere. It's what we do and it's expected of us as it should be.
"The owners of the kosher restaurant in Rome's Jewish Ghetto – a historic quarter in the centre of the city – were surprised when Mr Zuckerberg and Priscilla Chanwalked away without leaving a gratuity.
Waiters at Nonna Betta, which specialises in Roman Jewish cuisine, were amazed by Mr Zuckerberg's parsimony, not just because of his huge wealth but because of Americans' reputation for tipping generously, as is expected of them at home."