You try to sound helpful but just come off as a jerk. It's not much help to just say, "You should have know what you were getting yourself into."
I'm a programmer and a very technical person, and I still ran into the same problem.
iCloud photos on a device isn't working as people expect. My wife has an 89GB library and 64GB phone. We turned both iCloud Photo and Optimize Storage on on her phone and it filled up her entire phone leaving her with no space resulting in a phone that became totally useless. No app would open this point. This doesn't sound very optimized to a technical person as myself. Even the messaging on the phone says to turn Optimize Storage on if your device storage is running low. This doesn't work as one would expect because it still tries to use all the available storage space.
It should be smart enough to only download images as I try to view them. I don't need images from 2008 on my device unless I specifically try to view the image. That is what Optimize Storage should be.
Another option would be to go ahead and try to fill up the device. But as soon as another app tries to store something on the device remove images that have never been viewed on the device or that haven't been viewed in quite awhile.
With so many people have large libraries now this is something that Apple will need to address very soon.
