Is making predictions kufr?

It is shirk to claim knowledge of the unseen. So if I say that a person will become a bad writer when he grows up or will do bad in his exam am I claiming to know the unseen future? If it isn't shirk to make predictions of the future by evidences and through studying the Laws of Allah (may he be exalted and praised) what of baseless predictions or false predictions people make for personal benefit?