At the beginning of the story, it is established that the treasure, already "ill-gotten", is presided over and guarded by the Devil. In stories like this, that usually doesn't bode well for the character unlucky enough to meet him, or for the honesty to be expected in any of the Devil's words or objects.
Surely enough, when the Devil claims Tom (as part of their bargain) at the end of the story, most of Tom's worldly possessions are left behind, such as his home and horses. The horses are discovered to be dead, and the house burns down the next day. The treasure is discovered to be a chest filled with "chips and shavings"; small pieces of wood - a subtle reference to the Devil's identity as the "Black Woodsman". The actual treasure may never have existed, or it may have been taken to Hell - its fate, and indeed its existence in the first place, are unclear.
Part of the point of ensuring that the treasure followed Tom to Hell was to show that his earthly acts could not be separated from his character; it would be impossible for him to pass on his wealth to anyone else because it was bound to his soul.