Why do most entity or companies always believed that customer is a king as per their business involvement?

its because the customer is the reason why the business is there. if there are no customers the business would fail and hence not make any profit so the customer is king as they bring money into the firm.

Basic business. Customers generates revenue of the company, without any capital from sales the business cannot function. This is also true for NGO's or government organisation.

I concurred to your answer sir, because customers are the profit maximization of every business or company sector.

As per my experience customer is no more king he is a Dictator now. 

It is not only about "believing" but understanding & appreciating the fact that customers are "kings". Customers are always the most important visitors on business premises, they aren't an interruptiin to our business but the reason for the exisance our businesses. When you set up a company, you intend to serve customers not "trees", "buildings" or "vaccum". Without customes, a business will cease to exist. Therefore comapanies or organisation must wilingly accept & appreciate the fact that customers are "kings".

Its not about most entity, in every sort of business Customer is king because customer is the main source of revenue for the company. It is only customer that makes the keeps the wheel of the organizations running. If customer is not there, then there is no benefit for the company to do the business. Eventual aim of every business is to make profit and profit generation depends on the customer. Hence, it is right that customer is king for every sort of organization.

Rather than taking the appraoch that the customer is king see the customer as a partner in the business. His success is your success and therefore its mutally agreed that on one hand we deliver quality prodcuts and services and on the other hand we receive payment for it. Any issues that could prevent this must be discussed with the understanding of a win win outcome.

 

Customer is King because, 

 

He DEFINES the existence of your product or service (in the market) 

He INSPECTS the quality of your service or product 

He CONTROLS / LIMITS the inflow of funds to your account 

He PUNISHES / SUES you if you aggravate him with what he feels to be injustice 

He is NOT going to BELIEVE you again after you having damaged his faith in you 

 

Allegorically, all of the above gives you an impression that you are at his (customer's) command and therefore Customer is called a King.