Just my 2 cents: I have an Indian friend whose dad owns a college. When Demonetization happened, his dad asked all of his students to take cash and deposit into their account, and afterwards transfer into his account. To incentivise them he told them they would get a discount on college fees(off the books, ofc) for each cash deposit. Students were lining up all day for weeks to make deposits, many even got a lot of family members as well.

Another friend's family opened a luxury car dealership overnight, buying cars wholesale from legitimate car dealers who could then pass off any income as legitimate.

I'm very skeptical when anyone says black money was affected significantly by Demonetization.