Why do adult dogs chew on
bones, rugs, antiques, etc?

Well, by now we should know that it is given that dogs will chew bones to sharpen their teeth and keep them in good conditions. This could be an additional asset dogs have if struggling for survival.

Carpets, old things and others are chewed by dogs in response to a lack of attention from their family pack. Animals as well as children don't stand being ignored, specially if previously spoiled, so they do this even knowing that they will be grounded. It's better than being unseen. Jealousy and revenge could also be involved and that would explain why they basically destroy your best objects and furniture.