While the collective behavior of groups is important to understand when talking about security, the role of leaders is perhaps just as important.
Many of us don’t have the time to deal with issues beyond those in our daily lives, which is why we appoint leaders and give them some fraction of our resources to handle those issues. Every one of us has some small cadre of leaders we depend on, dealing with issues involving, among other things: spirituality (meaning of life), economics, and physical security. We typically keep those leaders that match our general “feel” for how those issues should be handled, and replace them only when their actions make us too uncomfortable and we have to handle more of the decisions ourselves.
The more power leaders are granted, the more of a role their individual personalities, intelligence, and experiences will play in determining the fates of the groups they represent. The specificity of that power is also important: whether it applies to ad hoc situations (such as crises or well-defined tasks) or a wide range of issues over a long period of time.
For example, ad hoc leaders such as military generals are assigned very specific goals, such as overcoming a well-defined enemy as soon as possible. National leaders such as presidents can determine and coordinate policy in areas that range from economic (such as trade and money supply) to social (setting and enforcing laws regarding how people interact with each other), military (starting an managing wars), and the environment (regulation of pollution, management of land use). Since ad hoc leaders are held accountable for meeting identifiable objectives, personal characteristics have their principal effect on the resources and time taken to meet their objectives. Policy leaders try to warp the world to fit their personal comfort zones, which, to be successful, must closely approximate the comfort zones of the majority of their constituents.