That title may seem a bit hyperbolic, I'll admit. But...hear me out. Because so many Boards of Directors are run by people who are well known and successful in the business community, it is often overlooked when or even expected that their businesses will be selected as vendors to the nonprofit organization. Sure, the board may go through the exercise of having the person leave the room while they vote on what vendor to use, but everyone there is "expected" to vote the way of the board member. Some boards may not even have Conflict of Interest policies in place that prohibit such practices (if yours doesn't, you can seek legal counsel or contact www.afpnet.org for assistance in finding a template).
The problems with that are numerous. Board members are not supposed to gain business due to the favor of the organization, and quid pro quo scenarios are a huge no no.
The Nonprofit Quarterly article linked below explains it well, and since the subjects are famous, hopefully the light will be shone on these oft occurring back room deals so that some good may come of it.
*Let me note here that the majority of people who join nonprofit boards do so with the best intentions and are there because they want to make a positive impact on the organization's mission. Mistakes are made often simply because of a lack of knowledge of regulations, laws, or ethical standards in the sector. Every nonprofit organization should have at least one regulatory "watchdog", whether that person is the CEO or a board member. The watchdog position is not a fun one, but it is necessary for the health of the organization.
Angelina Jolie Leaves Halo Trust over Board Members Paid for “Work”