It's easy to rack up money in The Witcher 3 by slaughtering hundreds and hundreds of bovine.
There are glitches, and there are exploits. This is the latter, as pointed out by YouTuber WhatMyGame. He outlines a quick way to start hoarding cash in a game without very much:
Let's break down how it works.
First, head to where some cows are hanging out at this spot on the map in White Orchard:
Next, slaughter the cows! You know, like this:
You're looking for cow hides, which can be sold for a pretty profit at shopkeepers nearby. If you meditate for at least two hours, the cows will come back. However, the corpses don't disappear...
Repeat this over and over, and you'll be able to afford whatever you want in no time.
Honestly, as tempting as it is, I wouldn't recommend doing this. You're not supposed to run around The Witcher 3 with a bunch of money, and it's more satisfying to earn it from doing cool quests for the people in that world.
Plus, it's not very nice to make a killing field of virtual cows, you jerk.