This is the right way to deliver software.

Produce working product first, validate the idea, stabilize the business, start generating profit, and then you can start optimizing your costs.

In fact optimization is by far the easiest part of the process because there are many system programming experts on this HN thread who consider these optimizations to be trivial.

Or optimize a bit earlier and prevent having to scale out to a bazillion systems.

This reasoning assumes you have access to infinite runway. You don't.