Something tells me that the phone numbers were collected in some other manner and the scam artists are just hoping that people have blockchain wallets without 2FA.
this is probable
i would think craigslist as a suspect, but unfortunately, i have a different phone number for craigslist dealings and the scam came in NOT on that number.
i don't think they are robocalling everyone with bitcoin scams like google adwords.. we wont be there for a few years..
i REALLY would like to figure out how they managed to get my number to robocall me with this scam so i can know who and how my personal info was leaked to spammers