Reliance Industries (RIL) Chief, Mukesh Ambani, has become the richest Indian in the world with net worth of $20.8 billion. He displaced steel giant Lakshmi Mittal, according to the recent data of 40 richest people, compiled by Forbes magazine. India is left with 27 billionaires from 40 last year and its 40 richest people maintain net worth of $139 billion.