Lots of great discussion here already. My own perspective is that it depends on both your goals and your source of funding. If your goal is to disrupt an existing industry, or create something brand new then speed is more important than frugality. If you are trying to create a business that solves existing problems but in a cheaper / better way (and nothing wrong with that) then frugality is more important as staying power is crucial.

In fact, staying power is IMO the most critical determinant of success. If you can stay in business then you can learn from your mistakes and pivot. In that case the discussion between frugality and speed is all about calculating your staying power, which goes back to your source of funding :)