Niching down: like putting your thumb on the hose

Just read this AMA on Relay from Bob Moore (Founder of Crossbeam) and absolutely loved the analogy. https://www.gorelay.co/t/i-m-bob-moore-i-m-the-ceo-and-co-founder-at-crossbeam-and-a-serial-saas-founder-ama/151/19?u=jonny

When you're niching down, you're putting your thumb on the hose. Water comes out faster (your ability to move) but you're not finding out the true water pressure (market size). Very apt for small bootstrapped businesses, because TAM is arguably slightly less important.

The whole AMA is really fascinating btw.

Alongside this and @mijustin wave analogy, what others do you find compelling?