The problem with trying to think in terms of “how do we get to $10 billion in revenue in 2050” is that you lose sight of the fact that your resources are very limited today. Staying focused on earning the first $50K of revenue allows you to concentrate your resources on a very well-defined short-term goal.
This is a brilliant little trick Wil came up with. Following the same logic I was also thinking that a better or maybe earlier goal of $2k pm in regular revenues might be better for a small bootstrapped web startup. For a frugal bootstrapper this may be sufficient to break even. Once you have proven to your self and others that you can make regular monthly cashflow and not just a burst of big sales. This could be an easy metric to yourself. Lets say your $2k revenue comes from 100 sales at $20. That is something you can understand and focus on. Our goal is to reach 100 monthly sales.
Updated, Thanks to Peter for noticing a slight math error.