Short answer:
They would go broke.
Long answer:
They don't have enough money to pay everyone for answering questions. And anyways, why would they want to?! If anyone should be paying for the answered questions, it should be the person asking the question. Anyways, this would not fit Brainly's business model, as they depend on subscriptions and ads for their revenue, and paying people to answer questions would not benefit them. And even if they did, it would probably be like 1 cent for answering 10 questions, as they dont have billions of dollars sitting around to pay answerers. However, they most likely wont do this because the issue of bots and spam answers, which could easily farm the system.
Thanks for reading this long explanation.
