A fanny pack is actually where my reserve insulin is at all times. And the pack is attached to me most of the time. There's also some sugar in there too.

People with T1 either have insulin pumps attached, or long-lasting insulin injected. They are not going to keel over from lack of insulin on most days, even if their pack is gone. Except if the pump stopped working hours ago, or they forgot to inject. Then they may be close to collapse already. And being away from sugar can become life-threatening quickly for people who shoot insulin. So overall they have a pretty good reason to always carry their stuff, even in an emergency. And yes, better always attached than in some bag than can get lost easily.