Exactly, I learned Linux in late 90s. There are a few new softwares like nginx instead of Apache but I can bring up a new VPS and set it up using essentially same knowledge from late 90s. With a CDN and caching, you really do have a massively scalable service.
Don't get me wrong, I love Cloud but I will never use it for personal projects. It just feels like renting vs owning. My personal projects will have bugs, and I don't want to be on hook for thousands of dollars.
Learn Linux/Sysadmin once, and you can likely use that knowledge forever.
As for performance, one of my projects can sustain 300rps which is more than enough. Sure it cannot scale automatically to thousands and millions but I don't think many projects have that requirements.
On top of that, cloud tech can't be "set and forget" because of deprecation of apis and services.
Agreed. I hear some saying it's nice to deploy on a lambda because you don't need to know anything about the runtime environment. But it's never quite true. As you say, you do have to become an expert in all the intricacies of these proprietary deployment environments to get the best out of it and avoid getting burned. So an amount of effort has to be spent, anyway.
But the drawback is that now you spend this effort on learning what is after all a proprietary product of AWS. While AWS is massively popular, the knowledge doesn't translate to anywhere else so it locks you in. If you spent similar time learning the basics of Linux deployment and administration, your knowledge is lower level and more general.
But where it really gets you is when things go wrong and you need to dig deep to diagnose. Can I attach a debugger or watch socket traffic or run bpftrace or do any kind of diagnostics at all on that lambda instance? Oh sorry no, good luck.
Unless your budget is so low you can't afford a $5 VPS and your traffic is so low that your lambda bill will never reach $5, you're really better off deploying on a VPS that you control and can debug. Keep it simple.