Yes, brainwashing really does work. But I don't think the famous version of this question was written by someone who intends to keep all the money for himself. Such a maneuver would be quite noticeable to anyone who examined the books, and those books would have to be open to auditors, no matter what country it is in. There's not a single government in this world that would resist having laws making it necessary for banks to be audited on a regular basis. Banks are, after all, where the money is. What government would agree to let them alone?
No, the big humanitarians really are humanitarian, on the whole. That they are sometimes motivated as much by tax breaks or press agents is not the point: that money does do some good.
But that does not end poverty. It's not a bucket to fill, where "a drop in the bucket" would make my point. Bill Gates and other well-known philanthropists give large enough amounts that they could fill a bucket. This is much more about attitude than money.
Another person with the exact same situation as myself would call themselves poor. But living in America, our worst (OK, most nearly worst) is much like some other country's middle class. Nearly everyone in America has a roof over their heads at night, even if it is a wretched homeless shelter or a flea-bag hotel. The few truly homeless are mostly there because they have not connected with those who could help them for whatever reason. Food, clothing and shelter are all available for free to any American who simply shows up at the right place and time. And there are outreach programs to go find those who don't know how to find the place or know the time.
But the bottom rung will always feel like poverty, no matter how comfortable it is compared to our average condition today. Lords and ladies of the medieval period did not have it as good as a welfare-recipient in America and other developed countries today.