--- shorter feedback loops: you can play through a game of Civilization in a few hours/days. There is no analogous real-life experience.
--- non-severe failure consequences: If you fail in Kerbal Space Program, there is no Challenger explosion
--- repetition: Real life usually doesn't provide similar conditions to make for valid experiments. Games can do exactly that
--- breadth of experience: In the same way books transport us, and let us visit other places and situations, games can do the same.