It is pretty easy to predict future where you are not involved in. I get more a general trend accurate for a few months. I also had predicting dreams reaching a half year out.
If people know their future, they usually change it.

So far I know, you can "predict future" in 3 ways.

1) You can feel things coming before they happen. It works well on short term, and can be trained.
It is very close to instinct, but better.
There is also a combination with telepathy, where you can predict someone calling you or meeting you.
I know some people who drive very fast, but don't get accidents because they can feel problems coming.

2) Via spirits. That is very commonly used by people with cards or with wild visions of the future.
Many people don't know what they are doing, so their predictions are very random.
Usually these predictions come with drama or theater.
Spirits are usually stuck in an astral space (between heaven and earth), and some of these astral spaces can reach beyond time.
So they can see things coming before they happen. Usually traumatic things.

Trickster spirits also like to make people afraid of things.
They also create psychological problems due to the fear they spread to people.

3) Via the soul. This is via meditation and via some dreams.
Before a person incarnated, the soul has a vision of what life is going to be.
Via this channel, the soul gets updates of new things that are coming in life.
These updates are like insights that come from within.
These insights are usually encouragements to make certain steps in life.
Or to calm down about challenges that seem too much.

The soul is also the reason that you can't predict the lottery.
The soul is choosing a path for your life, and does not want to deviate from it.
It also does not want to change someone else's path in life,
so it will not allow you to clearly proof something life-changing.