It’s just Markov chains running on a heap of poorly governed sources. Expensive because Markov chains are brutish to process.

But processors get faster and faster to calculate and conclude a chain rapidly. I could see why people think it’s intelligence since it is chains running through sources of human intelligence, but it’s not. It’s simple math from the late-1800s and we’ve been using it for predicting many things for a long time. Funnily enough, language was what Markov started with.