So you see this psychic, and he says to you, "Your child will be arrested for possession of illegal substances" but you're like "You're crazy!" and forget about the whole thing. A few years later, your kid is arrested for that very reason, and you remember this event, and write a report to
Psychics Weekly.
A psychic tells you that your wife's life will be cut tragically short. In two weeks she is diagnosed with metastatic lung cancer and has months to live. You tell your friends and family about this accurate prediction.
A psychic tells you that your status at your job is about to improve greatly. Next week, your boss calls you into his office and tells you that you're fired. You are amazed at the psychic's incorrect prediction and post about it online.
Wait a second, there's something wrong here... No one reports the hundreds of predictions that don't come true because a false prediction is a) not noteworthy and b) not memorable. It's like throwing darts and drawing bullseyes around where they hit; psychics are always right when they aren't wrong.
There's also what I call the "Nostradamus fallacy". If you never set a date, or even a range of dates on when something will happen, then, by sheer chance, something is bound to happen. This is especially true if you use vague language like
Beasts ferocious from hunger will swim across rivers:
The greater part of the region will be against the Hister,
The great one will cause it to be dragged in an iron cage,
When the German child will observe nothing.
Say I'm a psychic and, for whatever reason, choose not to use obscure language. I say, "You will die of malaria." You can never prove me wrong, because to do so requires that you are alive, so I can just said, "Oh, give it time... give it time..." If you die of something else, you won't be around to say anything on the contrary, and no one else will care about what some random person said to you when it turns out they were wrong. I say, "You'll break your leg", and, once again, until you die, there's still a chance that you will, in fact, break your leg. When you die, you can't prove me wrong because you're dead.