In my opinion the main reasons why craving causes suffering is due to the fact that one can't always get what they want. Hence that creates mental or physical issues for you. Since one cannot attain the object or thing they are looking for, a will to try harder and harder will come into existence. This may bring pain to you since not all things can be attained without pain. The Buddha knew that humans created ways of eluding their problems, by using drugs, alcohol and sex. He therefore looked for the original or the root cause, the evil of the evils. This craving persists and survives ones death. That why by I don't know by whose belief there are ghosts that have not gone to their righteous place - heaven or hell, if that even exists. For they have not accomplished their tasks on this planet. Death is only a temporary event in which the cravings do not stop, they continue only in a different matter.
Bhava-taṇhā
SeatedBuddhaGandhara2ndCenturyThe Buddha declared that as long as there were delightful and pleasurable things, the craving would persist. It arises and takes root in the senses, in the eye, in the ear, in the nose, in the tongue, in the body, and in the mind. It takes root in things like visual objects, sounds, smells, tastes, bodily impressions, and mind-objects, in the consciousness, sense impression, perception, will, craving, thinking, and reflecting. When an object is perceived to be pleasant one is attracted to it. But if it is found unpleasant one is repelled from it. Present suffering accumulates when people indulge in sensuous craving that lead to various forms of conflicts and quarrels or wicked acts like stealing, robbery or seducing the wives of others which results either in deadly pain or in death.