> But really, don't implement a user system if it is not needed.
Sure, i'm not necessarily advocating for a full blown RBAC implementation or something like that, merely something so that when your API is accidentally exposed to the rest of the world, it's not used for no good (at least immediately).
> Implement auth, if it is needed, implement monitoring, CI, CD, dependency monitoring, testing, everything, if it is needed.
> But don't implement it as dogmatic consequences of doing software development.
Now this is a bit harder to talk about, since the views here will probably be polarized. I'd argue that if you're developing software for someone else, software that will be paid for (and in many cases even in pro-bono development), most of that is needed, unless you just don't care about the risks that you (or someone else) might have to deal with otherwise.
If there's an API, i want it to at the very least have basicauth in front of it, because of the reasons mentioned above.
If there is a server running somewhere, i want to be alerted when something goes wrong with it, see its current and historic resource usage and get all of the other benefits running a few apt/yum commands and editing a config file would get me, as opposed to discovering that some bottleneck in the system is slowing down everything else because the memory utilization is routinely hitting the limits because someone left a bad JVM GC config in there somewhere.
If something's being built, i want it to be done by a server in a reasonably reproducible and automated manner, with the tasks are described in code that's versioned, so i'm not stuck in some hellscape where i'm told: "Okay, person X built this app around 2017 on their laptop, so you should be able to do that too. What do you mean, some-random-lib.jar is not in the classpath? I don't know, just get this working, okay? Instructions? why would you need those?"
Furthermore, if there is code, i want to be sure that it will work after i change it, rather than introducing a new feature and seeing years of legacy cruft crumble before my eyes, and to take blame for all of it. Manual testing will never be sufficient and integration tests aren't exactly easy in many circumstances, such as when the app doesn't even have an API but just a server side rendered web interface, which would mean that you need something like Selenium for the tests, the technical complexity of which would just make them even more half baked than unit tests would be.
Plus, if i ever stumble upon a codebase that lacks decent comments or even design docs/issue management, i will want to know what i'm looking at and just reading the code will never be enough to understand the context behind everything but if there are at least tests in place, then things will be slightly less miserable.
I'm tired of hating the work that i have to do because of the neglect of others, so i want to do better. If not for those who will come after me, then at least for myself in a year or so.
Do i do all of that for every single personal project of mine? Not necessarily, i cherrypick whatever i feel is appropriate (e.g. server monitoring and web monitoring for everything, tests for things with "business logic", CI/CD for everything that runs on a server not a local script etc.), but the beauty is that once you have at least the basics going in one of your projects, it's pretty easy to carry them over to others, oftentimes even to different stacks.
Of course, one can also talk about enterprise projects vs startups, not just personal projects, but a lot of it all depends on the environment you're in.
As for the money, i think that's pretty nice that you're paid decently over there! Here in Latvia i got about 1700 euros last month (net). So that's about 425 euros a week, or more like 850 if you take taxes and other expenses for the employer into account. That's a far cry from 100k. So that is also situational.