When I was young I was convinced that life beyond academia in all fields would be this super serious, mega competitive space where most everyone has everything figured out. That everyone who was there, in any kind of profession, would be super smart and really know their game inside out.
When I started my career I assumed frankly that my opinions were wrong, because of this. In my first job there were a lot of aspects that were almost the parody of how not to do things, yet even though I sensed this intuitively I convinced myself probably for the first year that I must be wrong and this must just be the way things are done in industry. That I would eventually figure out that this was the right way to do things. It's quite funny to look back on that in retrospect.
What I find most impressive about tales of young company builders and leaders, the classic Gates/Jobs/Zuckerberg etc, is not actually what they did but that they had the sheer temerity to do it at that age without first building their confidence in industry for a few years.
How did they know that they had the ability to build companies such as theirs -- surely were it possible one of the adults with 10-20 years industry experience would have figured it out already? How did they have the confidence to hold their own when confronted with such adults (many of whom I'm sure challenged them and competed with them for influence) as their companies grew? Truly awe inspiring.