What you said is very true, it's why I started up myself plus for greater autonomy.
The real struggle when starting up is realising none of your past experiences or the school college you went to is actually going to be that helpful.
"I did xyz under abc company". Sure buddy, as if you didn't have the benefit of the company and an already established brand in the market. You only leveraged it, anyone else can do it too.
Can you create a likeable brand from scratch? Do you know marketing and sales enough to get revenue on your own? Can you hire good employees, or train them to be better, or hire someone who's better and more experienced than yourself?
These are the real questions which kill egos and humble even the biggest narcissist. Starting up at least once in life should actually be mandatory training for college kids and experienced folks alike.