CEO of a company (or worse, non-profit!) and a member of its board creates another, for-profit company (in partial secrecy/lack of transparency) that the non-profit would eventually pay a lot of money. This is almost a fraudulent level of siphoning non-profit money.
Btw, this is hilarious - regular employees have non-competes in their contracts (sometimes void/illegal, depending on the local jurisdiction) and breaching them is an immediately fireable offense (sometimes leading to more severe consequences). You work on a small thing on the side? Better be careful, ask your manager/HR, risk it getting taken over by the company (luckily, IIUC this part is mostly illegal now in all jurisdictions that "matter" for tech).
But sitting on multiple boards where you have much more room and possibilites for creating conflicts of interest and damaging the company? All fine and common!