Calculate the net present value (NPV) for an investment project with an initial outlay of $5 million and expected cash flows of $1 million per year for 8 years, using a discount rate of 8%. Explain the net present value (NPV) as a measure of an investment's profitability, indicating the difference between the present value of cash inflows and the initial investment cost. Discuss the significance of NPV in capital budgeting decisions, investment appraisal, and its sensitivity to discount rate changes and cash flow estimates.