In the Bill & Melinda Gates Foundation's annual letter -- titled "3 Myths that Block Progress for the Poor" -- Gates says incomes are rising globally and the world will have "very few poor countries."
"Aid and innovation are what lifted them up," he said in the letter, co-written with his wife, Melinda.
"By almost any measure, the world is better than it has ever been," he wrote. "People are living longer, healthier lives. Many nations that were aid recipients are now self-sufficient. You might think that such striking progress would be widely celebrated, but in fact, Melinda and I are struck by how many people think the world is getting worse. The belief that the world can't solve extreme poverty and disease isn't just mistaken. It is harmful. That's why in this year's letter we take apart some of the myths that slow down the work. The next time you hear these myths, we hope you will do the same."
The letter said the three myths are that poor countries are doomed to stay poor, foreign aid is a big waste and saving lives leads to overpopulation.
Gates said those notions allow political leaders to try to cut aid, which he said amounts to 1 percent of the federal budget and is largely used to help pay for healthcare and infrastructure.
"The next time someone tells you we can trim the budget by cutting aid, I hope you will ask whether it will come at the cost of more people dying," he wrote.