The economy at the bottom is worth thousands of crores
The smaller and unknown brands and packaged goods sold in plastic covers without any brand is an economy that can easily exceed four thousand crores at the national level for a variety of cool drinks alone. Ditto for garments, particularly the women inner wear and clothing for children, cheap lungies, inner wear for men and so on, that would easily exceed a sure ten thousand crores, as most of these are sold in the rural areas,sometimes in villages. Add to this the entire range of goods,including cheap furniture made by local carpenters and so on, the total figure would exceed at least with thousand crores.The aspirational classes also upgrade so often and go shopping for costly second hand mobiles,cars and so on. So, it is not that those who are poor remain very poor at all times. A single graduate from their family is enough to uplift them to a better living standard.
No real economic data is available on the actual size of this economy. A form indication from trade sources is however available for specific markets
For example, Madurai has a huge night shop culture around the fabulous Meenakshi temple and a very large tourist traffic. The night shops offer a massive variety of both vegetarian and non-vegetarian food at very reasonable prices. A B school study revealed that this specific market exceeds an annual turnover of 250 crores. It provides direct employment to ten thousand people and students work part-time as well.
There may be more Madurai type of markets and members may please share such details.