Until the attacker bypasses your perimeter firewall by convincing an employee to download and install malware.

And so? This is true for any kind of infra!

You can't defend yourself from everything, but you can try to make you life easier by reducing the attack surface and make side movements more difficult.

Having employees (or system like bastion hosts) with unrestricted access is one of the recurring mistakes in such events. I can’t understand it.

Zero Trust is expensive to implement and the business people hear "at the end, the systems will ideally work as good as before".

It will take a few bankruptcies until security is taken seriously.