Yep! Undeniably and undoubtedly!

All successful entrepreneurs have attested to the reality, judging from what I have had already read about their success stories.

For one: 

Just imagine James Dyson, who introduced the revolutionary bagless vacuum cleaner bearing his name to the world, went through more than 5,000 prototypes and stretching with R&D for more than fifteen years before he became successful. 

A WISE QUOTE FOR MONDAY MORNING

"Failure seldom stops you. What stops you is the fear of failure. I have never encountered it, as I have only ever had temporary setbacks. Never walk away from these setbacks. On the contrary, study them carefully - and imaginatively - for their hidden assets. If you want to double your success rate, double your failure rate."

~ Sir James Dyson, founder of Dyson Appliances & Britain's inventor extraordinaire, who has given the world its first revolutionary (but expensive) Dual Cyclone bag-less vacuum cleaner; he has in fact spent over 15 years working in the cellar before finally launching the product in 1993, which became the country's best seller in 2 years;

Wow! What a valuable lesson in sheer persistence & unwavering perseverance!

[I understand that James Dyson's entrepreneurial exploits & learning experiences have been well-documented in his own autobiography, 'Against the Odds', which I haven't yet read;]