Can Library folder on iMac be moved to iCloud Drive? My disk in my iMac, High Sierra is about full. The biggest culprit by far is the /User/myname/Library folder which is taking up 96 GB. Since I have over 100 GB of icloud storage could I move the Library folder to the icloud drive and create a link? How do I do that so iMac still can access the Library.  If this is a stupid question I apologize.

OmniDiskSweeper says ~/Library is 73.9 GB. Don't know where the other 22 GB went.  From OmniDisksweeper the storage hogs in ~/Library are:


Application Support - 20 GB with MobileSync being the major player
Containers - 18 GB  with com.apple.mail being the major player
Mobile Documents - 18 GB with com~apple~CloudDocs being the hog.
No. 

Firstly, relying on an internet connection to access preferences, caches, and other system/user 'working' files is likely to be problematic. As mentioned in the comments, iCloud is handled locally by a folder in the user Library, so having this itself in iCloud might be confusingly recursive.

It's worth checking whether all of that 96 Gb is necessary: it may include iPhone or iPad backups, which are frequent culprits for taking up space. Use an app like OmniDiskSweeper to search the library, sorted by size. That will show you what is taking the space, and you can then make a decision about whether it can be moved or deleted.