Last week, I pointed out that the "Giving Pledge" founded by Bill Gates and Warren Buffett  wasn't really all that impressive considering that those same billionaires have wired the economy so that they get richer much faster than they can give their money away.

In addition, some of the Giving Pledgers support charities that are self-dealing (like the Trump Foundation) and many billionaires only pledged to give away 50 percent of their wealth. To state the obvious, 50 percent of a billion dollars is still an insanely huge wad of cash.

While some of the Giving Pledgers have wills that leave everything to charity, it's telling that very few are willing to give away all their wealth before they die. Hey, giving it all away after you're dead isn't exactly a sacrifice, considering that you can't take it with you anyway.

Just to show it can be done, though, here are three billionaires who actually gave their entire fortune away whilst they were still alive:

Feeney came from a middle-class background but unlike many "self-made" billionaires he never seems to have forgotten where he came from. Feeney acquired his wealth selling selling duty-free luxury goods, which is perhaps ironic since he has always lived rather simply. Notoriously publicity-shy, Feeney kept his identity secret for his first 17 years of charitable giving. Now, at age 89, he lives in a two-bedroom apartment with his wife, having given away his entire fortune of roughly $9 billion.

Truth be told, steel tycoon Carnegie was a bit of duckhead (feel free make the appropriate letter substitution on that last word). For years his idea of charitable giving was ostentatiously handing dimes to random street urchins. Carnegie's foundries were sweatshops from hell but Carnegie thought his workers needed, say, a public library more than they needed a safe workplace. (Like I said, a bit of a duckhead.) Even so, Carnegie did manage to give away his entire fortune before he died.

Yu started at the absolute bottom: pulling a rickshaw around the streets of Shanghai and then working as a prisoner in a labor camp. Yu subsequently made his fortune as an hotelier starting, incidentally, with a rent-by-the-hour flophouse that catered to street hookers. However, Yu quickly went legit and amassed a fortune of many billions. By time the time he died in 2015, he'd given all his money away, leaving nothing to his two sons, because he was afraid that they'd turn into entitled trust-fund brats. Like the kids that will inherit the 50% of the obscene billions that their "Giving Pledge" parents didn't "give."