1. You mistakenly bet twice on the same event - loss
2. You add an extra zero to the stake - loss
3. You take the wrong side or total - loss
4. You take the wrong side but realize your mistake and bet 2x on your intended side. Loss.
5. You take a -1000 fav in a long time for whatever reason - loss.
I could go on, you get the point. On the other hand, in poker the dumbest play in the world gets rewarded by a huge pot pretty much every minute.