15. Marc Andreessen, Co-Founder, Netscape:

Marc Andreessen revealed that he and other members of his company were still blaming themselves over was probably Square. He said, Jack Dorsey is one of the most exceptional founder-CEO’s in the industry and that he is now accepting it as the biggest mistake they did when Jack had first came in to them. He said in an interview given to Bloomberg TV in 2012, "We over thought the deal and we probably just should have said Jack Dorsey, check. And write the check. That's probably the big one.” reports the Business Insider.

16.  Rio Caraeff, President and CEO of VEVO:

For Rio his biggest mistake taught him the lesson that always in one’s life family comes first. He said that, when he was young, he was traveling on a business trip when at the same time, one of his family member passed away at his home. At that time, he had decided not to travel back home for the funeral at any cost as he had made the decision that his work is more important than anything at that time. So, because of that mistake he said that he is regretting for that situation now. He revealed this mistake in an interview with the Fortune in 2009.