Cybersecurity consists of multiple concentric rings of deterence, detection, and diagnosis.
If an attacker get to a system, the IT organization lacks sufficient paranoia to do an effective job.
Many IT managers are focused on meeting deadlines and budgets, specifically for the CIO's / CTO's latest new shiny toys. Things that add time and cost, including quality assurance and security, are to be avoided.
No manager ever gets credit, a bonus, or a promotion for the resolving the cyberattack that never happened because of great security.
Paranoia is a cyber security analyst's best friend. Nobody wants to admit that their systems are vulnerable. Everyone wants to feel like they are doing a great job.
It's best to bring in vetted, outside white-hat hackers to challenge your infrastructure, systems, technicians, and management. The outside, vetted white-hat hackers will not be subject to organizational blindness.
It's amazing how many compromising things that shouldn't happen, actually can.
Myself and a system admin found a gaping hole in a security vendor's product was manipulated, by accident, to allow someone to login to System A as root (admin/god) only to find themselves on System B (which they had not even connected to) logged in as root. In no sane, logical universe should that be able to happen, but it did.
A vendor's security product opened a 'worm hole' to other unintended systems. We were astounded, because that is they type of exploit black-hat hackers dream of. I would have never intentionally thought of that attack vector because it was so illogical. This is an example of my logical blindness. An outside, vetted white-hat hacker would have been more likely seek and find this vulnerability on purpose. We only found it by accident of luck.