And even if you just go by numbers, it's not likely that technology will be available to the entire world population any time soon.

As of 2008, 22.4% of the world population was earning less than $1.25 per day[1]. 870 million people (one in eight) were suffering from chronic undernourishment in 2010-2012.[2] Even if they could afford smart phones or internet service, it's not likely that you could sell them a lot of stuff on the internet, or convince companies that they should pay to advertise to them.

Also, it's the poorest countries that have the highest birth rates. Some developed countries, like Japan or Italy, will soon have declining populations.

Companies like Facebook have already picked up all the low-hanging fruit -- the people in developed countries who can easily afford internet access and smartphones. Getting additional subscribers will only get harder once they have to start looking to lesser-developed countries for new subscribers. The era of exponential growth may have already passed.

[1] https://en.wikipedia.org/wiki/Poverty#Absolute_poverty

[2] http://www.worldhunger.org/articles/Learn/world%20hunger%20f...

You'd think that would be a capitalist incentive for corporations to act to better the living standards of the global poor, so they can become potential customers and consumers of their products.

There is. For example, the free market - to the extent it has been allowed to exist - has done a lot to move China forward in very short amount of time (and particularly given the disaster their country was coming out Mao's reign).

Several former Soviet countries that were exceptionally poor have made good progress after the fall of the USSR. Hong Kong was practically a banana republic at one time, and quantum leaped forward very fast courtesy of Capitalism. Singapore used to be an irrelevant back-water nation.

You'll find that in most of the worst countries today, there are structural impediments that make it nearly impossible for the free market to reach the poorest. Often it's extreme levels of corruption, backed with violence; other times it's very protracted regional warfare (eg in central Africa); and other times it's a mixture of cultural and bureaucratic as in parts of India.

http://www.foreignpolicy.com/articles/2010/02/22/africas_for...

This strikes me as another variant of the "just 1%" fallacy of the bad old dot-com bubble days. Back then it was common for a startup to enter an industry and use an overly simplistic model to justify the viability of their business. Often it went along the lines of: this market has X (big number) in total annual revenue, if we can capture just 1% (or some even smaller fraction) of that market that's Y dollars (another big number).

Of course, these are just silly math games to hide the true difficulty of their broken business models. It doesn't matter whether you're talking about 1%, 0.0001% or any fraction, that doesn't make acquiring that business easier. The difficulties of growing a business into multi-million dollar revenue territory are still there even if the total market is huge.

There's no shortcut, and even as the market gets bigger there still won't be a shorcut. There are always trillions of dollars on the table waiting for businesses to pick them up, but it typically takes a lot of hard work to build something with any degree of value.