The game where I reported the first bug was D2. The game I was referring to in the last paragraph was WoW. I used 4 different methods over nearly 10 years to exploit the same bug. The first 3 produced an error message when the item duplication was unsuccessful. It was only unsuccessful ~10% of attempts, but I was careless enough to cause too many error messages to occur in a short period of time. I believe that's why they were patched. However, the game devs didn't investigate enough to realize my intent when causing those error messages. So they neither took action against my accounts for using the exploit (though my accounts were closed for exchanging items for real money), nor did they ever fix the underlying bug that allowed item duplication. They just fixed my methods for exploiting the bug. Then, I'd find a new method and continue.
I made enough to pay off a car, credit card debt, student loans, build a small chunk of savings, make a small down payment on a house, and live free of financial stress for a few years. It helped me immensely when I was desperate, but it didn't end very well. I wrote more about it in my blog listed in my profile. Here is an HN discussion about one of the posts that generated some interest: https://news.ycombinator.com/item?id=8439648
I made enough to pay off a car, credit card debt, student loans, build a small chunk of savings, make a small down payment on a house, and live free of financial stress for a few years. It helped me immensely when I was desperate, but it didn't end very well. I wrote more about it in my blog listed in my profile. Here is an HN discussion about one of the posts that generated some interest: https://news.ycombinator.com/item?id=8439648