There are exceptions always, especially when an entrepreneur think he will do that thing his whole life (as Mark Zuckerberg is ought to do).
If you are a first time entrepreneur and you have the mindset of "I like to start things, over and over again" then it's easy to give up larger chunks of your first company because you know you will come back to start another startup after a while. Serial entrepreneurs belong here.
If you think "This is something I'll be doing my whole life and I couldn't see myself doing anything else" then yes, it's harder to give up good chunks of your first and last company. Zuckerberg or Steve Jobs and others like them belong here.
Steve Jobs owned ~1% of AAPL shares vs Zuckerberg's much larger stake in Facebook. They are nearly on opposite ends of the spectrum of that particular spectrum.
In the beginning they both owned a lot. And if it wouldn't be the luck of Sean Parker giving Zuckerberg his board seat and sided with him then Zuckerberg might have not been in charge at FB now (he would still own shares).
At one point, when Steve Jobs was fired from Apple, he sold all but one share of Apple. So his 1% was the result of converting his NeXT shares, not original Apple shares.
If you are a first time entrepreneur and you have the mindset of "I like to start things, over and over again" then it's easy to give up larger chunks of your first company because you know you will come back to start another startup after a while. Serial entrepreneurs belong here.
If you think "This is something I'll be doing my whole life and I couldn't see myself doing anything else" then yes, it's harder to give up good chunks of your first and last company. Zuckerberg or Steve Jobs and others like them belong here.