Edge Cases Exist

Sure, the odds of generating a duplicate UUID are astronomically low—like 1 in 340 undecillion. You'd have better chances of getting struck by lightning while winning the lottery. But here's the thing: "low" doesn't mean "impossible."

So naturally, you skip the uniqueness check in your database because "it'll never happen." Fast forward six months and you're debugging a production incident at 2 AM where two users somehow got the same UUID and now half your data is corrupted. The PM is asking questions. Your manager is asking questions. You're asking yourself why you didn't just add that ONE line of error handling.

Fun fact: With UUID v4, you'd need to generate about 2.71 quintillion UUIDs to have a 50% chance of a collision. But Murphy's Law says it'll happen on your watch if you don't handle it. Always handle your edge cases, kids.