Don't you think there's something of an opportunity cost, though? If someone like Linus had dedicated all his time to a startup (he did spend some time at Transmeta, but still had time for Linux), perhaps he would have never accomplished what he did. Perhaps similar arguments could be made about people like Guido van Rossum. Obviously there are various paths to success, but how many people made their cash, and then went on to do a seriously successful open source project? I'm sure there are one or two out there, but I think mostly it's a one or the other situation.
The relevant section is called "Two Routes."
Linus seems to have taken organic route, gradually
arranging his life so he could spend more time
on Linux. Startups are usually an instance
of the other strategy, the two-job route, of
which they are the most extreme form.
(For a few very lucky people, a startup can
also be one's life's work. But it's usually
all one can do to make a startup succeed without
also satisfying that constraint.)
Yes, I've read that essay, and liked it. What I'm getting at, though, is that isn't it possible that by taking the startup route, by the time you 'get there', yes, you have time to do whatever you want, but you've blown your chance to do something else?
You could say that those guys went straight to step 2: Work on something they find interesting, ignoring money. It probably is a one or the other situation, but the results end up being the same -- living life as one sees fit.
Both making a lot of money and doing a "seriously successful" open source project are pretty rare, so even if the two are independent, you shouldn't expect many people to succeed at both of them.