Here is a perspective from a very season finance professional.
http://www.subramoney.com/2015/09/meeting-interesting-people/
As one can see, there is a section of people who are willing to pay even 10% interest per day for a small sum, which they in turn use, to earn their livelihood.
Access to finance is a critical factor for growth at levels of society.
Imagine this, even with so many PSU's, NBFC's, Private Sector Banks etc we are still a hugely under banked society so what different is a handful more of payment banks going to make to the overall pie ?
I think there is a enough business for many more institutions at these levels.