If your store experiences $X in annual theft losses, insurance premiums will likely exceed $X. Insurers need to cover their costs and make a profit.
Insurance doesn't prevent theft; it shifts the financial burden. The economic impact still exists.
Insurance is most effective for low-probability, high-severity events rather than frequent, smaller losses like shoplifting.
Some shops in San Francisco have stopped buying insurance against break-ins, due to the increase in frequency.