How is MGM still down? [video]

I am not on security side, but MGM is still down due to cyberattack, but my question is how?

Was everything connected to the internet?

Was there one point of failure in their whole network?

Was there a hole from the outside internet to their internal network?

Were they not using a big email provider like GMAIL or Outlook to prevent phishing?

Did they not prepare or practice for an attack like this?

Will their head of IT security or director of IT be fired over this outage?

Thanks, I am on development side. So all the times that security teams were difficult with myself or my team, now I understand why.

They even filed an 8K noting the attack - https://d18rn0p25nwr6d.cloudfront.net/CIK-0000789570/8912b17...