This tldr isn't very accurate. And the article isn't really that long. Worth the 20-something paragraphs of time.
But, to offer a slightly better summary:
Voltaire earned ~ half a million livres over about a year after discovering a broken lottery with a mathematician friend. The guy in charge of the lottery was fired, and the lottery was cancelled.
Voltaire used that money for additional investments, substantially increasing his wealth and allowing him to freely pursue his writing. The mathematician used his winnings to fund scientific research and expeditions.
Directly from the article: "As he later observed, “If you want to make a fortune in this country, it is enough to read the king’s orders-in-council.” In other words, if you want to get lucky, read the small print."