Contents of Images Folder in AddressBook - 3 million-plus files and counting, tens of gigabytes I was getting sick of running CleanMyMac to scrape back a few GB of space here and there, so used DaisyDisk and discovered in /Users/user/Library/AddressBook/Images something like 50+ GB of space taken up. I checked online and it appeared safe to delete, so I trashed it. However, trash has been emptying since last night and it currently says "3,041,134 items deleted" and it's still going up. 

As I looked through these files, they appeared to be every photo associated with every one of my connections on social media. I mean, random photos of people I'm Facebook friends with but haven't talked to in years. 

Other than needing to pare back my Facebook network, can anyone tell me anything about why these would all be collected somehow and why and how I can stop that from happening again? Thanks.
It's possible as you mentioned these files are coming from macOS trying to synchronise your Facebook contacts with your Contacts.

This setting is in System Preferences &gt; Internet Accounts.



As you can see there is an option to include you Facebook contacts in your address book, and additionally the Update Contacts button which tries to match your contacts and update details about them like birthdays and photos.

If this is going wrong for some reason it could create a large amount of files which as you've pointed out while not individually huge would take a very long time to move or delete.

Try turning off this feature, and waiting for the files to finish deleting, it may help to reboot between turning off the feature and removing the files.