How to build a sustainable startup to help the poor?

You don't make money from the poor? IF YOU DO THEN IT'LL LABELED AS EXPLOITATION I think the right word is NGO :)

Make government pay for it. Say you build Byju for poor, give it away free for Govt school students. Charge a nominal price to others. Once you have some traction, do a big PR campaign. Then hire a political lobbyist to reachout to all political parties. Government will first do a pilot project . Then they may scale. Keep an NGO arm if required. Hard but possible. PS: I had done something similar a decade back but our pilot project failed.

Launch a fancy gutkha company. Helps the poor alleviate from their problems of daily life. Capture atleast 20% of their daily earnings + subscription service that grants them access to female virtual bots who teach them to spit their gutkha in hygienic ways with gamification. If they’re low on money introduce p2p lending to purchase their gutkha with hidden interest rates and fees. Also launch a co branded credit card with lounge access perks and cashbacks tied to more gutkha purchases. GTM with Sunny leone on the gutkha pack for a chance of meet and greet + Paan spitting competition with lifetime access to gutkha for the winner.