The risk that something like this is what happened is why Bitcoin companies (and other companies that deal with money) should have mandatory vacation policies for employees. With a mandatory vacation policy, it's much harder to a single person to commit fraud, since keeping up a fraudulent scheme requires daily attention to create fake books and records. https://sourcegraph.com/blog/mandatory-vacation
A mandatory vacation sure would have put a stop to "Brian Molony"'s systemic theft from CIBC much earlier. iyww Biran Molony was the real life person behing the movie "Owning Mahowny".