1. There are dozens of famous and wealthy Indian classical musicians - Hariprasad Chaurasia, Zakir Hussain, Amjad Ali Khan, etc. There are hundreds if not thousands of lesser known musicians who make a living by teaching and performing in small venues.
2. Of course, many talented people are prevented by social custom or poverty from following their dream, but its simply not the case that there are hundreds of unrecognized geniuses walking around.
3. Ravi Shankar's success was not totally accidental - he didn't just "happen" to become popular. He was a great communicator, and he appropriately structured his music to be not too complex for beginners and westerners to understand. If you listed to his rivals like Ustad Vilayat Khan for example, they went the opposite way and added layers of complexity and did not achieve popularity among the masses.