Often I hear through the grapewine by people working in certain businesses that outside competitors had no way of succeeding in this niche. This was due to internal networking in the company. Neither would they get into the company, because jobs were spread internally, nor could they compete due to unfair advantages like knowing the right politicians, having the financial means to influence them. Also not to forget the huge information advantage big companies gathered over time.
In my experience, most companies whose founders were previous employees created sustainable businesses, whereas those who were total outsiders hardly made it. But they also couldn't get internships due to internal spreading of jobs of any kind and friends and family.
How is it possible to have a good business idea in a niche without having worked in the niche as an intern or employee?