The title might sound dumb, but the real goal is to learn more and eventually get better at simple system designs like in the terrific posts below:
https://www.listennotes.com/blog/the-boring-technology-behind-a-one-person-23/
https://anthonynsimon.com/blog/one-man-saas-architecture/
There are a lot of resources on distributed systems and interview preparation where the focus is on FAANG scale, distributed setups, exobytes of data, which is cool if you are working on such a project but most likely you are not. I am not, for example.
I really admire these articles because their authors have such a great understanding of many different aspects of development.
While reading them, I noted to myself that I personally can't even answer with confidence what a single reasonably fat server can handle with just a web server and Postgres.
I have also always worked with managed DBs because it so happened that the companies I worked for are active cloud users.
Even worse, even at mid sized companies, a lot of complexities like load balancing and DNS are handled by dedicated teams and you just have to read the documentation and hope that K8s managed by the admin team does everything for you.
It really makes me feel incompetent to realize that what the authors of these posts implemented on their own, is not something I could do.
On the bright side, I really think I'd like to fill the gaps.
Maybe, there are some resources that build things up incrementally with a focus on simplicity but at the same time do not take anything for granted?
I have read Designing Data Intensive Applications, it's my favorite book but, honestly speaking, even the title says that it's about large scale.
The good news is you should stop worrying about this stuff, and just build. You'll eventually run into bottlenecks and can address them then. That's how best learning happens anyways. Premature optimization is fun and intellectually stimulating, but rarely gets you closer to delivering value.
My rules of thumb for starting out: