It should be $0 because this was a credential stuffing attack (Using breached passwords people reused), and affected people who knowingly shared their data with other people.

23&me didn't leak data, they didn't have any database breaches, their infrastructure wasn't compromised due to negligence...etc The majority share of negligence is in the users here.

Yes, they should have MFA, but also no, most sites and services don't force you to use MFA to begin with, and that's not a regulatory requirement anyways.

This is, for the most part, the fault of the folks using terrible security practices such as refusing passwords and sharing their data with other users. And this is a shitty precedent to set where the technical reasons for this event are thrown out the window in favor of the politics of it.