When you think big, too big, you risk missing some of the most important steps.
You might miss the first, second and third step. The steps you need to take before you're able to sell that company to Google. Before you're able to sell 1 million copies of your book.
When you're all excited about your new super big idea you might forget some critical steps.
Like how that app might actually get onto people's phones. Or why it would even stay there when every single day tens of thousands of apps are being released. Same holds true for self published books. Or every other product out there.
I know you're different. Your thing is different. But the truth is, it's not.
People only have limited amounts of resources. They have limited budgets. Limited time. And a limited attention span. People only have a limited amount of time every single day to read books. Or blogs. Or whatever.
So it's very likely they're going to read someone else's book first. Someone they trust already. Someone's books they've already read in the past. From someone they know already.
Its also very likely that they're going to use someone else's app. Or product. Or what not. For the exact same reasons. That's why most of us don't really use more than 6 apps a day.
And that's the real power of thinking small. Of thinking one step at a time. Of thinking about these small things first. Before you start thinking too big. Before you're thinking about selling millions of copies and selling your thing to Google...
[Related: I stopped giving a shit a long time ago]