Much like a weather forecast, a psychic looks at the likelihood of events taking place if the current path is being followed by the person. In other words, if you continue the way you're going, this is what will likely happen.
However, things can change.
Everyone has free will. This means that people can consciously change the direction their life is taking. It also means that other people in their life can make decisions that affect the outcome of events.
It's a very tangled twist of directions and human freedom.
My best advice is always this: "The best way to predict the future is to make it happen."