ttruck,
The above answer is about the most accurate you can get on a generalized question such as yours.
Almost all expeditors are Independent Contractors which translates to being small business owners.
This is like any other business where the particular decisions of the owner and the managment of all the variables can make a huge impact on the ultimate success regarding income.
This is why laws were unacted years ago prohibiting Franchisors from making revenue and income promises of any sort. Some people invest in a Subway and lose their shirt, others become millionaires.
It would be helpful for you to search and study this forum for the many related posts regarding income and expenses as well as researching the business aspects before making your move.