Why did Marley visit Scrooge

Marley's ghost, ‹transparent and bound in a long chain made of cash-boxes, keys, padlocks, ledgers, deeds, and heavy purses‹enters the room. Scrooge claims he does not believe the ghost exists, but soon he admits he does. Marley says his spirit has been wandering since he died as punishment for being consumed with business and not with people while alive. He has come to warn Scrooge and perhaps save him from the same fate. He tells him Three Spirits will come to him over the next three nights. Marley makes incoherent, sorrowful sounds, then leaves.