Take a broader view of hacking. A system is not just its code, it's the people that run it, too. If you want to break into a system, they are frequently the best point of entry.
To paraphrase from the first season of Mr. Robot as they're looking over surveillance pictures of a secure data center compound with high walls, biometrics, security cameras, and 4 armed security guards;
"How do you break into a place with no weak points?"
"How do you break into a place with no weak points?"
"I see four weak points right there."