They talk like that because you want them to.

These people are defined by their success. Audiences want to hear about it, often looking for insights. For obvious reasons nobody knows exactly what they did right and thus end up sounding as if in doubt, not least because they don't want to sound pompous.

So when you listen to tech millionaire turned hacker Ben Bitdiddle, unless (A) you insist he talk about his surfboarding experiences or (B) Ben doesn't mind coming through to you as an egomaniac, the observation described here is very much expected.