So what's driving Zuck to stay in the game? Does he really believe in the work he's doing? Is he feeding his narcissism? Does he really want more money? Can he just not let go of his baby?
Can you name the person who invented the printing press? The person who invented the cotton gin?
Perhaps most notoriously, he invented a fire department that would only put out your house fire if you sold the property at the price he wanted. Negotiations went on as the house burned.
Columbus himself was arguably a businessman.
To rationalize it my own mind, he must simply continue being CEO since that's what he enjoys doing.