We don't know that. We don't know what happens past the event horizon as it's impossible to see and our current laws of physics break down at that point.
Shortly out of college I remember going to see Sephen Hawking give a lecture. He was adamant (at that time, not sure if he ever changed his mind) that we'd never know what was inside a black hole. I thought boy that was a stupid thing for a scientist to say, who's to say we'd never figure out the physics of it. The theory of relativity completely changed our understanding of physics, and looking back it's a pretty simple thought experiment to prove it. Another theory might come along that blows open what we know about black holes.
And the force behind them is, you guessed it, gravity. Our current laws treat it as a constant, we don't know how to harness it, not really. Made me think Hawkings was an alien plant at the time. Lol.