I think it's interesting to talk about how "act your size" can also be wrong. Sometimes fake-it-til-you-make-it is the goal.

This is a really interesting point, I think.

In my opinion, it depends on what your larger goal is. If your goal is to eventually become a big business, that changes your approach and "fake it till you make it" gains some validity. In a sense, those sorts of businesses are less "small businesses" and more "large businesses in their infancy".