Someone please help me explain this to my mother

[Blarg]

I don't think you're in any position to say what maximizes her money. And certainly imputing charitable motives to her or implying or inferring that she's one of those rare souls who doesn't care about money is pushing pretty hard on a foundation that falls somewhere between very shaky and non-existent.

If you have to "believe" what's happening, it's not a fit way to think for an adult. It should stand up to scrutiny with or without belief or desire.