A breaker is a protective device
A circuit breaker interrupts a circuit when current exceeds what the conductors are rated to carry, or when it detects a fault condition. Tripping is the protection working, not failing.
Common causes
Overloaded circuits happen when more equipment draws power on a circuit than it was designed for. Short circuits and ground faults are fault conditions caused by damaged wiring, failing devices or moisture. Aging breakers and loose connections can also cause repeated tripping.
When to stop resetting
If a breaker trips more than occasionally, trips immediately after reset, or is accompanied by heat, odor or discoloration, stop resetting it and have the circuit evaluated. Repeated resets do not address the underlying condition.