If I were a less honest person, I'd have my way to get rich:
1) Post a Job Ad on LinkedIn
2) Reach out to applicants on LI's messaging.
3) Ask the applicant fir their DOB, Location, and last 4 of their SSN
4) Reverse engineer the full SSN from that data
5) Sell that identity on the dark web
If I'm really lazy I'll automate it with a shell script.
(was just asked for that info in a char on LinkedIn before I was told the client name)
The other thing I should add is that even if all parties are sincere email isn't secure, and I don't believe LinkedIn's messaging platform in end to end #encrypted.
This is Seán Reiser's Personal Mastodon Instance. It contains a month's worth of toots. Older posts are archived on his blog at https://seanreiser.com/blog