Agreed on the "prepared to fail" section. I've done freelance work before but I never really considered it a real business for some reason. Th clients I had were from referrals or people I knew, I didn't have to put much effort into finding clients.
Now it's a different story altogether. I've not officially launched my product (still under development), but it feels much more like a business than anything I've ever done. It's very exciting! And kind of scary... strange. But I agree with most of the article for sure, good stuff.