These are the same statistics that move spammers as well. Say, if only "2%" of the victims pay, they are making a fortune...

Sad but true, the net is filled with scammers/phishers/spammers etc. Same thing goes to the malware that encrypts part of your data and demand a quick ransom for release, to make you panic and not give you time to confirm or research online about it. Most just bluff, but some do harm, especially to popular insecure OSes and some buggy email clients (or web browsers) that like to "display" attachments...

I have seen the like of those not just in emails, but also social media, etc. Best way is to ignore them, send them to the spam folder, etc.