Yeah your right, as long and you do the numbers and you got the sense of adventure and drive to pick it up on the way, go for it.
Also if you understand that it isn't automatic that things will go right which means the truck could break down, the company could not deliver on their end, etc.
If you up for taking those chances, and you know you are responsible enough to save your money and handle your business and learn all you can as you go...you definitely will come out making more money than a new company driver.
Problem is most people are not ready for taking on that complete package that comes with stepping out there.
They just hear the more money part!
Like the man said though, if fit for the challenge....ask questions, do the math and take the leap.
Just be honest with yourself, if your not ambitious and about handling your business, go company first.