Adventurers often acquire items and encounter expenses that are not easily classified as gear to be toted about or thrown in a backpack.  Sometimes and adventurer will invest their gold into a shop or purchase a home for their "off time" or other recreational uses.  For instance, I once had a Wizard PC who purchased a small farm at the outskirts of town and hired a family to tend the farm and aid him in breeding War Dogs.  He paid excellent rates to the family and earned a modest stipend from selling his War Dogs to other adventurers and local lords as well.  Other than providing him with a place to store his bulky valuables and seclude himself for research, the farm provided him with a constant supply of War Dogs ready to battle and a steady income to pay the local taxes and make reasonable repairs to the home.  This allowed him to spend all of his gold gathered from adventuring furthering his arcane studies.