Asked how he's different today from how he was in 1994, Gates said: "20 years ago I would stay in the office for days at a time and not think twice about it -- so I had energy and naivete on my side. Now hopefully I am a bit more mellow but with a little extra wisdom."
Gates said that digital money that isn't anonymous -- unlike bitcoin -- has the potential to help the poor because it has low transaction costs, and is thus viable for transactions involving small amounts of money. "Over the next 5 years I think digital money will catch on in India and parts of Africa and help the poorest a lot," he said.
Asked for an update on his foundation's efforts to promote the design of a better condom, Gates said the work is still in progress.
"This is a sensitive topic. The idea was that men don't like the current design so perhaps something they would be more open to would allow for less HIV transmission. We still haven't gotten the results. One grantee is using carbon nanotubes to reduce the thickness," he said.
Gates also fielded many questions about his philanthropic work with the Melinda & Bill Gates Foundation, saying at one point that "the greatest tragedy" is that of children who die in the developing world from preventable diseases or who never reach their potential due to malnutrition.
"We need vaccines and nutrition to solve this. We are making progress but not fast enough. Cynicism is the biggest barrier," he said.
He expressed optimism that polio can be eradicated worldwide soon and that in 20 to 30 years "gross inequity" will be almost eliminated, and along with it statistics such as the fact that a child in a poor country is 30 times more likely to die than a child in a middle income or rich country.
Literacy and nutrition are "basic things that we can afford to give to every child," he said.
Juan Carlos Perez covers enterprise communication/collaboration suites, operating systems, browsers and general technology breaking news for The IDG News Service. Follow Juan on Twitter at @JuanCPerezIDG.