Paul Graham has posted his responses to an Interview About Web 2.0:
The idea of building something popular then figuring out how to make money from it was born in the Bubble. It sounds irresponsible, but it works. Requiring founders to have a carefully worked out plan for making money is not hard-headed business sense. It’s what hackers call “premature optimization.” The really important thing is to make something people want.Most startups that failed during the Bubble failed because no one wanted what they built. There may also have been a few that were building something good, but failed because they burned through their funding too fast. So that’s rule number two: don’t spend money.
If you can make something people want and not spend money, you’re 90% of the way there.