The Witcher 3: Wild Hunt is a game full of opportunities and possibilities, and among so many variants, some players have found ways to exploit these options to their advantage. Recently, WhatsMyGame shared a way to make money by slaughtering cows, but honestly, there is a much more practical, quick and effective solution - and it's one that won't anger PETA.
As shared by PowerPyx, players can get rich as soon as they reach the city of Novigrad (you can do it early on in the game). Look for the merchant in the Hierarch Square and buy the cheap Shells and Sea Shells (automatically renewed when you leave the merchant). Now look for the blacksmith in the vacinity and destroy the shells you just bought to make pearls, that you can sell for 100 Crows each. In a few minutes, you can make a considerable ammount of money and repeat as often as you want.
That said... The Witcher 3: Wild Hunt is a game built around a very strict economy, and this exploitation destroys the reality CD Projekt Red is trying to create. It's up to you whether or not you use this exploit...