A change in personal goals. If you're 25 and have the opportunity to sell your startup for $5M, you would most likely take it. Now at 27 you're bored, and have millions in the bank. You don't necessarily need to be rich any more, but being king is fun. You start another company.
This is what I was trying to get at. I think there's a whole class of people out there who just like to build things.
Being king means responsibility and headaches. Being rich is nice but once you get past a certain point it all becomes abstract wealth as the author points out.
What's left after that? For a lot of the best engineers I know, reverting to '6 year old w/ big box of legos' mode and just building something to see how high you can go.
