I'm good at predicting what people will do. Or, at least I think I am; maybe it's confirmation bias. But I try anyway. I read their faces, I look at their past actions, I look at the situation and watch them take in facts, then I make a snap judgement about what will happen next. Humans actually do this all the time. We fill in the gaps with predictions. We can finish each other's sentences, or fill in the middle part we missed.
Also, as a human, I tend to act in ways that are predictable to other humans. It's a self-reinforcing cycle — prediction and predictability — that makes human society possible.