I have an iMac. Apple puts everything in iCloud drive. How can I avoid having to pay Apple for more storage? explain inside?

iCloud drive has limited storage and when full you can “pay” for more storage. I am furious about this. Here’s the deal: If you remove something from iCloud drive it REMOVES IT FROM THE COMPUTER! I have gnashed my teeth. My IMac is 1TB. I have a 2TB external hard drive. I seem to be trying to do the impossible.
I have considered other operating systems. I believe Apple hamstrung its users with this! Until now I loved my Mac. This desktop is my only computer device. Anyone?