@mattly I bought this book in the early 00's (I suppose after 2004, but probably not much after that)
https://www.amazon.com/Malicious-Cryptography-Cryptovirology-Adam-Young/dp/0764549758
In which the author pretty accurately predicts the "Encrypt your shit and make you pay for it" approach.
I don't know that I really grokked it all at the time (I was 17), but I suppose at least you could say someone was thinking about ransomware back 20 years ago at least.