Three IIM alumni, who co-founded BillDesk in 2000, will make around half-a-billion dollars each from their combined 31% stake in BillDesk after Prosus' $4.7-billion acquisition. However, MN Srinivasu, Ajay Kaushal and Karthik Ganapathy said they'll remain a part of the payments company. "We aren't the typical young startup founders," Srinivasu said, as he and Kaushal are 53 years old.