Here's why:

* Smaller Size and Mass: Red dwarfs are the smallest and least massive stars. They have far less fuel (hydrogen) than larger stars.

* Slower Fusion: Their smaller size and mass result in much slower nuclear fusion rates in their cores. They burn their fuel much more slowly.

* Low Temperature: Red dwarfs are relatively cool, which further slows down fusion processes.

As a result of these factors, red dwarfs can live for trillions of years, which is significantly longer than the estimated lifespan of our Sun (about 10 billion years).

While red dwarfs are common, they are very dim, making them difficult to observe.