Computer
Today I'm thinking about the last bit of an oft-quoted line:
The cloud is someone else's computer.
The “computer” part can fall to the wayside. Each cloud provider presents (what they advertise as) unique services that try to sway you over to their side or goad you to keep spending money with them. I've found myself diving into the esoterica of each service from the AWS console far too many times to count. However, beneath the veneer, these services are still computers. They operate under fundamentals that have been in place for a long time.
I learned about this just recently. A web server on AWS wasn't responding as normal. Why could that be? The first thing I did was jump to the AWS console to see if it was anything on AWS' side. Nothing. After actually connecting to the instance via SSH and running a few commands, the problem became clear — nginx had stopped. After starting it back up, the web server could be accessed properly.
The above error had nothing to do with troubleshooting AWS but troubleshooting the services running on the Linux instance that happened to be hosted on AWS. It had more to do with computer fundamentals than the cloud provider.
That's why I appreciate that this self-taught cloud computing guide which emphasizes Linux & Networking fundamentals before digging into a cloud platform.