The basics are actually not that difficult to learn and understand.
You are in business to make money.
How specifically is Additive Printing changing the world right now? How is it changing your specific industry?
When is the last time a salesman told you the whole story?
Knowing the basics about different types of 3D printers and printing methods is key will keep you from wasting a lot of your time.
What are leading-edge researchers and companies working on now and what will it allow you to do one day?