Shri Swaminathan,
I wish to narrate one real life incident. Back in the 1960's I was working in (today's) Mumbai, staying in a bachelors' cot accommodation (4 people in one room-4 cots) paying Rs. 40/=per month. I used to stay in King's circle just next to the present Shanmukhananda Sabha. (Incidentally I was one of the first batch of members of that Sabha when the inauguration was done.)
During my spare evenings (I used to work in a factory on rotating three-shift system) I used to visit a very small book store, which comprised a single wooden almirah, placed on the door ledge of a street cornet Irani restaurant (run by a Parsee) who had let that ledge portion to a tabra at a very nominal rent. I had some interest in religion and though somewhat foolish, I used to curtail my hotel (eating) expenses and use the few rupees to buy books on religion, mantras, philosophy etc., from this tabra. Since the overheads were practically nil, he used to sell his books at a very small margin of profit. In due course he came to stock pavithrams (not "pouthram" ref. post # 7), darbhai, poonal, different kinds of panchangams, date calenders catering to the religious-minded people and simple pooja accessories, etc.
This gentleman had many children. After a few years his grown-up children used to come and help the father in managing the book-shop. Then I left Mumbai. When I went back after 8 years the bookshop had expanded into the previous Irani hotel area and had become a central hub for all things which tabras needed for their religion, plus, it had a huge collection of books. when I enquired about this to another petty shopkeeper who had been doing his trade from a nearby shop, said that the old tabra's children have purchased the premises and have greatly expanded their father's business. That is the "Giri Trading Agencies" of today!
What I am trying to say is that it is not only through the academic rank route that a tabra can improve his economic condition, he/she can also excel in the business line, if there is the proper business instinct and resourcefulness.