The most important thing for investor trust right now is that the trends are going the right way. In 10 years people will start seeing the writing on the wall for the current distribution model.
Is this what photo printers did to prints? People don't buy prints as much because of digital photograph, but when they want prints, people still pay someone else to print them.
Small scale manufacturing can only compete with large scale manufacturing where speed, customization, or luxury are important enough to pay a large premium for.
Bezos is an investor in Makerbot. (http://www.crunchbase.com/company/makerbot)
I'm sure he's well aware of the trends in 3D printing and will position Amazon in the market appropriately.
* Mobile phone * Bottle of beer * Sweatshirt or * Pear
What do you say?