Reliance Industries Chairman Mukesh Ambani added $17.4 billion to his net worth in 2017, making him the biggest Indian billionaire gainer this year, according to Bloomberg. Adani Group Founder Gautam Adani, whose infrastructure group is India's largest coal trader, gained $5.66 billion this year. The world's largest steelmaker ArcelorMittal's Chairman Lakshmi Mittal gained $5.13 billion this year.