Also, I would say that the difference is not much "scaling" a CRUD app for request/seconds, but for engineers on a single codebase/service, also architecturally. It's one thing to work alone on your project (which will probably handle k req/s, it's very easy nowadays with classic PostgreSQL and some other queues like RabbitMQ if you need event-based system). It's another to work on the same system with 100x more features, complexity (either in the same monolith or in different micro-services), and especially understand how to be pragmatic and solve problems you did not account for.
No amount of study can prepare you, other than first years at work. Afterwards, in my opinion, the challenges become improving the technology to scale more, and management.