Zook was mopping floors at a bank out of necessity - he needed the money, and janitorial work was all he could get at the time. This narrative that he was supposedly a "vice president" and not dusting the blinds and vacuuming carpets in the evenings after closing time has always been hogwash. A personal friend of his was an executive at the bank and didn't want to embarrass him, and did so by showing him on the website as some kind of higher-up. They would parade him around in front of customers during the day every now and then so he looked legit - Zook was bored and had nothing else to do. His buddy even lent him the suit he would wear, as Zook had hocked his suits (and damn near everything else) to pay his debts. They thought having a former head coach supposedly on staff would be impressive to customers, but it ended up backfiring: after seeing Zook, scores of people took their banking business elsewhere. The "executive" experiment ended quickly.
Those at the bank have always denied he was a janitor, but he was spotted at least half a dozen times in the evenings through the blinds, scrubbing away - yellow gloves on and everything. Once he was even wearing one of those red bandanas on his head like Aunt Jemima. It really is the most honest, honorable, and useful work he's ever done.
How he lost all his money isn't fully known, but drugs and/or gambling is the most likely reason. He never really earned any of his outrageous pay during his coaching days, so it's poetic justice, I suppose. He survives these days on his social security.