Alex Barrow, The Street--United Parcel Service (UPS -Get Report) investors aren't happy about Amazon (AMZN- Get Report) developing its own delivery service. In fact, they're very worried about it. Sure another delivery company (no matter how small) is never good for business. But investors are blowing the Amazon threat out of proportion. There's a strong bear case for UPS, but the main drivers revolve around macroeconomic headwinds. Amazon's possible transition from customer to competitor is not a real factor.