[murderfs]

Instability just means that they don't naturally return to stable flight. Fighter jets benefit from this because when you want to make a maneuver, you're not fighting the plane's natural inclination to stay where it's pointing. You don't need particularly powerful hardware to do this kind of control, quadcopters are an even more obviously inherently unstable example, because any thrust imbalance will immediately make it roll. Quadcopter control loops only need to run at a few hundred hertz to achieve stability.