The average office worker receives around 144 irrelevant messages per day, of which 24% have attachments. Email attachments sent in copy are accessed only 6% of the time.
https://www.mxhero.com/post/save-the-planet-replace-email-attachments-with-file-share-links
"With email attachments representing, very conservatively, around 17,000 files per worker per year, we conclude that in a 1,000-person company a staggering 17 million file copies are created every year as a result of email’s file-sharing methodology."
https://www.ipswitch.com/blog/3-problems-email-attachments-file-interception-data-leakage-compliance