“Potter offers Bailey economic security when he comes to him for help after his uncle misplaced significant funds from the Building and Loan).”
Potter offered him financial security before the lost funds (a three year contract in exchange for the building and loan. After Potter sole the 8K he called the sheriff to arrest Gearge.
It was very obvious that the lure of a better job was simply to get control of the savings & loan. George Bailey would have found his job evaporating soon after the ownership was transferred.