Once Badshah Akbar' s army was engaged in a prolonged war. As a result his royal wealth ("shahi khazana") was nearly exhausted.
He asked Birbal, "How to replenish my wealth."
Birbal: You can get it from Dhanna Seth.(merchant).
Akbar was amazed as to how a trader/ merchant could have so much money. Still he went to Dhanna Seth.
Dhanna Seth offered: Badshah Akbar, I have huge wealth, take as much as you want."
Akbar: Dhanna Seth, How did you accumulate so much wealth. Tell me without any fear of punishment.
Dhanna: I earned it by adultrating grains & spices.
Akbar got angry, he took all of Dhanna's wealth and ordered him that from then on he would collect the horse dung  in his royal stable. Dhanna agreed.
Years passed by. Again Akbar had to fight a long drawn battle. Again his royal wealth exhausted & again Birbal advised Akbar to go to Dhanna Seth for help.
Akbar wondered : Birbal, I had ordered him to work in royal stable to collect horse dung, How on earth he can have such a wealth."
Birbal: Badshah, you can ask him but only he can help you.
Akbar went to Dhanna. Dhanna gave Akbar huge wealth.
Akbar: Dhanna Seth, I had earlier taken all your wealth, How did you accumulate it again?
Dhanna: From the stable - incharge  & horse attendants. They used to underfeed the horses. I threatened them that I will complain to Badshah that they did not feed horses enough, hence the horse dung quantity was less. So they bribed me to keep silent.
Akbar got very angry again & ordered Dhanna to start counting the waves at sea & returned to his Palace with Dhanna's wealth.
As luck would have it, Akbar fought another war, royal wealth emptied out and once again Birbal advised Akbar to go to Dhanna  Seth for help.
Akbar could not believe as to how Dhanna could earn so much by counting waves at sea.
Akbar asked Dhanna for the help.

Dhanna: Badshah, Take as much as you want but this time around I will not change my profession.

Akbar: Ok, but tell me how did you earn money by counting Water waves at sea.

Dhanna: Very simple, I used to stop merchant's ships & boats far  away from sea shore. I showed them your orders that I  was counting waves & their ships & boats would disturb or break the waves hence their ships or boats should stay away. Badshah, these merchants then used to bribe me to let them reach the shore & unload their merchandise.

So Badshah understood that Dhanna Seth can earn by engaging in manipulations & bribery from any profession.

Demonetisation or no demonetisation, the Dhanna Seths of our society will always find a way to earn & accumulate black money.