Business Organization and System

What are the main reason the people become entrepreneurs?

What are the main reason the people become entrepreneurs?
Why this particular domain of market research and servicing domain for the entrepreneurs?
Before a entrepreneur or start a business, What are the problems you have to faced?
What risk you have to faced, become an entrepreneur?
What is difference between an opportunity and an idea?
Why is it important to start a new firm when its “window of opportunity” is open?
Talking about the online industry, advertising things has completely change the scenario form way back you have started?
How different is entrepreneurship on an international stage as compared entrepreneurship on a domestic level?