Spare derailleur hangers are crucial for remote rides, but the decision to carry one shouldn't be taken lightly. The added weight and bulk can be a burden, and not everyone needs one. It depends on the rider, terrain, and bike.
If you're a road cyclist, the chances of needing a spare hanger are slim. But if you're a mountain biker, it's a different story. The rough terrain and frequent crashes make it more likely that you'll need one.
But let's be real, some road cyclists are paranoid about mechanical failures. They carry spare tubes, pumps, and tools, even on short rides. It's overkill, in my opinion. But if it makes them feel better, who am I to judge?
In the end, it's up to the rider to decide. Just don't be that guy who carries a spare hanger on a flat, paved trail. That's just ridiculous.