Also, people become far more risk-averse as their careers progress. This is particularly true in high-paying jobs like software development; its hard to walk a

Also, people become far more risk-averse as their careers progress. This is particularly true in high-paying jobs like software development; its hard to walk away from $100k+ job to start your own project, especially with a wife and kids depending on you. The younger you are the more risks you can take. Also, as you said, software evolves quickly. So its completely reasonable for a 25 year old to have mastery of a new and exploitable technology... makes for an interesting entrepreneurial dynamic.