India, Feb. 9 -- A single reckless decision, a moment of curiosity, or one bad choice is sometimes all it takes to derail an entire life. A recent Reddit thread asking, "What's the fastest way you've seen someone ruin their life?" has sparked thousands of chilling, heartbreaking responses from people sharing real-life experiences they've witnessed up close. (Also read: Are there 'any positives' to travelling to India? Reddit discusses polarising reality of 'disgustingly magical' country )

One of the most haunting accounts came from a user who recalled how simple curiosity spiralled into irreversible loss. Sharing the story of an ex-boyfriend who tried heroin "just once," the Redditor wrote, "He loved it. Said it was the best feeling of h...