Charity doesn't stop at the cure, but continues to shift with progress.

If a big public charity is able to cure a cancer type (eg. lung cancer), then it's next aim would be to try cure another cancer type. Let's just say they are somehow able to cure all the cancers, and therefore they cured cancer, then there's distribution of the cure, with a focus on 1st world but then it would have to go to developing nations too. Along the way, there may be issues that arise in recovery from the cure, so money towards helping survivors there. Shift goal, shift goal, shift distribution/priority of donations, on and on and on. For the proper charities that do want to meet their goals, something like this is what they'd do.