People try what might fail only when they trust the group to catch them; take away the net and they do only the safe tricks.

The claim

People take risks that would advance a group only when they trust the group to catch them if they fail. Without that protection the able still perform, but only what they know they can land; the few who take risks anyway are valuable, but their gains end when they leave or fall. A sense of being protected, produced by shared values, turns risk-taking from an individual exception into a habit of the whole group.