Ask HN: Is working on a startup a terrible idea for a graduate student?

I'm a graduate student at a good school. (I study hard science, but I'd prefer not to specify which department.) The thing is, this spring I decided to build my programming skills by working on a project; pretty soon, one of my friends said, "That's not just a toy project, that's a business, and I want to be your partner." He's a smart, successful guy, so I got really excited. I've been more motivated and had more fun working on my project than I've ever experienced with academic work. And I've gotten positive responses from a lot of people.<p>But then reality set in. Most startups fail. Most startups take all your time. The most likely scenario if I throw myself into this project is that it'll interfere with school, and I'll wind up with no PhD and a failed business, and I'll be screwed. I really want to at least code up a prototype. But going further than that... I'm worried. I don't want to ruin my life just because hacking is fun.