It can take a billion years for a black hole to die
To some people’s relief, a black hole does die. But maybe not in the usual fashion you would think. In 1974 there was a theory by Hawking that eventually black holes lose their mass and die out. His theory was a bit complex, but it checked out.
The emission of tiny amounts of photon particles causes them to die. Radiation happens due to quantum effects around the event horizon. This process is slow and takes billions of years, if not more. As of now, scientists believe that since the beginning of the universe, 13.8 billion years, only the smallest black holes would have died off as a result of emitted radiation.