Which populations are we talking about here? I'm wondering what's a large majority, and what the certain age is.
I do think talking about prioritization when it comes to things like charity, or philanthropy is silly though. At least after a certain point - giving people access to the internet is a wonderful thing, not as wonderful as curing Malaria, but still extremely beneficial.
I think I'm going off a statistic I saw a while ago saying malaria was the #1 killer of humanity throughout it's history. Obviously that's changed now, but I do think it effects large number of African countries and tropical climates.
I dug up this who article:
http://www.who.int/mediacentre/factsheets/fs094/en/
But yeah it was more hyperbole to make a point. If we are talking about prioritizing something to lead to a better quality of life, you'll have more of an effect if you can keep citizens living longer than educating them, not vice versa. I'm not saying education is not important, it obviously is, but it's one of those 'crawl before you walk' scenarios where crawling is staying alive and walking is education.
I don't think anybody is for not giving the internet to these people. It just comes down to which fulfills a basic human need more? But yes you will get millions of people tackling every type of problem so in the end you'll have it all eventually.
Edit: here's a better article.
http://www.who.int/features/factfiles/malaria/en/
So about 3.3 billion people are at risk of being infected by malaria. It's preventable but that's about half the population that could be killed to a disease.