7 extremely wealthy people who choose to live frugally

Michael Kovac/Getty Images for Vanity FairFacebook founder Mark Zuckerberg.

Frugality is a subjective term. To the average Joe it could mean eating meals at home or scouring the internet for cheap flights. But to a billionaire it means showing up to work in a T-shirt and jeans, driving a Toyota or Volkswagen, and, in some instances, foregoing the purchase of a private jet or lavish vacation home.

A handful of frugal billionaires appear on our list of the richest people on earth, and each one has his own penny-pinching habits.

From eating lunch in the office cafeteria with their employees to residing in homes worth a fraction of their wealth, these seven self-made billionaires — many of whom are also generous philanthropists — know the secret to keeping their net worths high.