You are completely right. Prophets aren’t the only ones that can have visions.
In fact, hallucinations, which are created by the mind, are regularly reported. They can be caused by many factors such as illicit drugs, alcohols, migraines, mental illnesses (schizophrenia, …), extreme tiredness, medications, sleep disturbances, tumors, and so on.
Whoever has visions, should immediately stop taking illicit drugs. If the visions still persist then it is very important to consult a doctor.