what is origin of profit??

Answer 1

I'm not sure I understand what you are asking: "buy low, sell high"? the etymology of the word:
http://www.etymonline.com/index.php?term=profit
the role of the word or concept?

In any case, one characterization I like is Drucker's comment:

there is no such thing as profit; there is only the cost of doing business and of staying in business. Business can survive only when its profit is able to meet the demands of its future.

Since Peter Drucker essential created the idea of management per se as a profession, he was no idiot, not particularly naive, and not at all ignorant, so however crazy this statement seems, it needs to be approached with respect.