Russ Roberts talks with Sam Altman, the CEO of Y Combinator, who says

I’ve never written one in my life. At the stage that we are operating at, it’s irrelevant. Like financial projections also we never look at. …We would rather them spend the time working on their product, talking to users. What we care about is: Have you built a product? Have you spoken to users? Can we see that? Can we talk about where it may involve? The really good interviews end up being this back-and-forth brainstorming session about all the things they can do. The future directions the product can go in, what you can do to get users, what they can do to improve it. We care about stuff like that. But in terms of business plans or financial projections, nothing.

There are people, not all of them professors of business schools, who swear by business plans. I am, like the Y Combinator folks, skeptical of them.

Also, Altman is bullish on biotech.

I’ve really come to believe that those two things, low cost and low cycle time, are the most important things for startups in a given area to be successful. But now, in biotech specifically, which is an area where we’ve been active recently, the costs and the cycle time have come down quite dramatically. And so you are able to have a startup that for a few million dollars or in a year or something can get something really meaningful done. And that’s a brand new thing.