Designing Data-Intensive Applications: The Big Ideas Behind Reliable, Scalable, and Maintainable Systems

by Martin Kleppmann

It is well known that the majority of the cost of software is not in its initial development, but in its ongoing maintenance — fixing bugs, keeping its systems operational, investigating failures, adapting it to new platforms, modifying it for new use cases, repaying technical debt, and adding new features.

That is only the case if the software is successful. Consider the likelihod of success as well as whose money you are spending when deciding how scalable to go.