A corruption-ridden society creates a rentier section and runs every risk of an implosion!

Rentier class is one who live on rent income. This is in fact living on income from assets and not labor. How does corruption create rentier section. This needs some elucidation.

It refers to the rent-seeking section and a very familiar term in Marxian literature. A class of people who exploit the system to their gains without contributing anything to it.

An old couple who has put in all their earnings on property and wanting to live on the rentals cannot be called as exploiters since they are in need and are living off their hard earned savings...There has to be a clear distinction between those who have many rental properties and living off it and the kind I have mentioned...

As I have added and indicated that it is used exclusively and selectively in the context of exploitation. The instance you have cited does not include this section. Savings is deferred consumption. Those who save for the future are actually sacrificing present consumption to protect their future and it is one form of contribution on their part. Banks or any institutions employ their precious savings for certain developmental purposes and compensate them through whatever term you choose. Surely,it's not a one-sided affair. Let me cite a typical example of rent-seeking. When middlemen milk the poor farmers and buy their farm produce by paying them terribly less and earn rent by selling to the retailer at a much higher price. This rent-seeking activity in no way benefits the society,neither poor farmers nor ultimate consumers.