When you come to the Sales at Risk tabs, the potential loss amount of a product that is sold only once or a few times may seem high.

This is because by default the system uses 'last 7 days' average to calculate the next dates. But as you can see in the popup, the longer you set for the forecasting, the better you get the result. What you should do is select the products, and use the Bulk Edit > Set forecasting days option.

For setting forecasting days have a look at here.