Seems like a lot of the pushback on this is about whether in releasing this playbook @sama and YC are (i) making a value judgment on unicorn startups vs other businesses, and (ii) serving their own agenda. Personally I don't understand either of these positions.
On (i) it's like attacking someone for releasing a book of muffin recipes by saying "you think muffins are the best food in the world! I only bake cookies -- do you think you're better than me?!". In fact they just like muffins, they have a lot of experience in baking muffins, and instead of keeping their recipes secret they want to help other people bake the best muffins in the world.
On (ii), again my personal reaction, I don't care if it's self-serving. It also happens to be very helpful to me.
Small businesses, large businesses, "lifestyle" businesses, unicorns -- they all take a lot of effort, not to speak of other life commitments. In fact there is a maximum amount of time they can take (24 hours minus a few hours for sleep per day) and depending on your personality you will likely dedicate more or less of this time regardless of the scale of the venture.
I don't think whether it's a $10m business or $100m business or more is a choice based on personal preference, it's based on the nature of the idea you find yourself compelled to pursue.
For example, I used to be an antitrust lawyer. I was often in the office until 5am, and that was as an employee. I worked HARD. I thought I wanted to work less so I quit my job to start a small business. But it turns out that the idea that I have been excited about for the last few years is not a small business, it could never be one even if I wanted it to be. It's the kind of idea that will either be huge or it will be nothing. When you are standing on the brink of that kind of endeavour a few helpful words, a playbook if you will, from someone who knows how it's done can be very helpful indeed.