They earn their fortunes in any way you can imagine. Some inherit, some speculate, some found something…but they accumulate wealth.
Some give all at once, but many give in increments- eg, $1 million over X years and then a balloon payment. Or a chunk this year and smaller amounts divided over the next X years. Again, it can depend on how they want tax benefits or they won’t liquidate the asset that will fund the gift all at once. Or, whatever.
Interesting article here about a recent gift to Bates, which notes some other big donations
http://www.pressherald.com/2017/05/16/maine-family-donating-50-million-to-bates-college/
"did they donate all at once or with smaller amounts over a period of time? This is regarding the hp and Stanford example you noted. "
I think that it was more like larger amounts over time. Also, I am pretty sure that David Packard was NOT trying to get his son or daughter into Stanford, but rather was trying to help an organization which he felt was worthwhile. As one example of his generosity, I will note that there is a Packard Electrical Engineering Building at Stanford. There is also a Lucile Packard Children’s Hospital at Stanford (Lucile was David Packard’s wife). Neither of these would have been inexpensive to build.
Very successful people are going to vary in terms of the extent to which they want to donate their money to worthwhile charities or whether they want to keep it or leave it to heirs (of course “keep it” doesn’t last forever).
I will also note that Stanford University itself was founded based on a huge charitable grant by Leland and Jane Stanford, and was dedicated to Leland Stanford Jr, their only child who had died from natural causes.
Developmental admits are still way better than legacy admits. At least donations help the school and kids who need help. Legacies are born advantage.
Please, let’s not get into the old ‘bad legacies’ argument. There’s so much misunderstanding of the standards all these kids are held to.