The man was initially a billionaire He bought huge amount of rice (at $10) and sold it to poor people at affordable prices ($1). In this process, he lost so much that he became a millionaire
Alternate solution: Based on exchange rates, for every dollar he spends on rice in the U.S., he earns two Indian Rupees. So, he could become a millionaire in Rupees without spending a million U.S. dollars
