One of these days, I will solve this funny charity business. There is a lot of people who would love to donate Bitcoin to actually make a difference but there is just too much scope for mistakes/ scams in the name of charity. This is a problem that needs solving.
To be fair, this charity these members were running was amateur hour at best and not representative of bigger, professionally managed ones--but that's not to say that those other charities don't have their problems with money management and/or fraud, because quite a number of them have.
The method is very simple. Build up a reputation here. Get into managing communities locally. Then do questionable things and blame it on others for not understanding, coz you are BUSY. Gotta love that false sense of entitlement.
Honestly, I don't think this was planned as a scam from the beginning at all, and if I understand correctly they did distribute some funds/goods to needy people. That leads me to believe that somewhere along the line having all of that bitcoin in their hands just became too much of a temptation. The pilfering probably started small and escalated (that's an assumption based on how embezzlement cases usually progress), and by the time it got out of hand they stopped communicating anything about the charity in hopes nobody would notice.