As people get older, they solidify; they’re set in their habits, and aren’t likely to change in major ways. They hurt a lot more, they’ve experiences failures, and they’ve been through the ringer. They know what it’s like out there in the real world, and that a lot of it involves some level of fear. It’s understandable to have fear; we all do! It’s human. It’s ok to be comfortable, but not all the time. Not if you want to progress and remain healthy in mind and body, as we are meant for constant adaptation. It’s the expectation of fear that makes it so hard for people to alter their habits.