One of the things that makes the security field so interesting is that it’s mostly about people. Security efforts (even if assisted by security systems) are usually directed at people, and largely executed by people for the protection of people. The most important assets are usually people, most of the highest risks we try to mitigate have to do with people and most screening and assessment efforts are attempts to distinguish between people who pose a security risk and those who do not.
If you can’t understand people, you can’t fully understand security.