It is worth going further back in the history of economic development to understand today. In Europe and the US, vast fortunes were made and built on serving the majority of the population, who up until the beginning of the 20th century, were poor. Selling humble hygiene products, cheap paper backs, low-price candies, flat cap cloth hats, whatever. Many of today's inherited business elite can trace their fortunes back to that time. When poor people get the opportunity to eat well, keep clean, learn, and be able to think past today, they rapidly move to becoming the middle class. Without that crucial first step, you are avoiding an even bigger potential middle class market and keeping your horizons too low.
Imagine this - only 27 million people file income tax returns in India, miniscule by any standard, making the 98.6% being in the BOP as stated in the report, seem all the more plausible. With such an huge segment of the population being stuck at the bottom, all claims of 'fast' becoming a developed nation is nothing more than a myth.
If the top Global markets are spoilt for choice, and middle class ... be it in the third world or the first, is saturated ... the matrix of business values can easily justify catering to the BOP. Say I have a cotton plant in Alabama. One need not be a genius to fiugre out that an Alabama cotton plant is a no go. Why don't I set up my old and aging junk machinery in say Brazil or India, and produce for the local BOP market. Here's the kicker ... by saving American jobs, I can reach into the US sustainability industry pot-of-gold thanks to my local politicos! And export knowledge, IP, design's...this is also called business.
In due time, I have seeded the BOP mass mart and work towards a windfall payout. Good to quote here the example of one Swedish match Co. who turned thier focus on India.
I also take issue with your use of data from 1990. It's ben 19 yrs....that's an unacceptable long time for data sensitive 21st century. Note that the pace of poverty alleviation is accelerating for past 25 yrs., albeit not mirroring your investment banking type returns.