It would be interesting to know how the hackers gathered all this data of emails and passwords.
I know that account cracking is a thing.AFAIK,there is a software called Openbullet,which is being used for cracking various online accounts.
All the things needed is the software,configs about the websites,combolists(a bunch of emails/password combinations),proxies and a VPS/RDP,so the software could run 24/7.
I know that Coinbase accounts have been cracked before,by using this cracking tool,but I don't know how the hackers managed to bypass the 2Factor Authentication.I guess that there was a flaw in the 2FA system,that was exploited.
The other option is all this account data being leaked from the Coinbase database,I guess.
Anyway,I hope the hackers will be caught and the people are getting back their coins,just like Coinbase had promised.