I don't understand this at all....

considering Oprah makes $400+ million per year since she retired . . . .

I mean to be fair sometimes it can take years to make movies. Granted they still get paid astronomically more.

It's supposed to encourage others to donate. The more the better

You don't understand why getting people to donate is a good thing?

If it's a good cause, give what you can.
What others do or don't do isn't important. I mean, unless you're just looking to assuage your own guilt...