They may have been approached by people saying "What can we do?" and set up the fund as an answer. As you think it was complications from pneumonia, there's no "main chairty" that springs to mind.

It is also possible that the fund is set up to be untouchable by anyone but the surviving twin, and they know their own financial situation and tendancies and feel it is best that way. Don't make assumptions of financial well-being just because of salaries and such, many people find it easy, whatever their wage bracket, to live beyond their means.