WOW! There seems to be a few opinions flying around here, not to mention egos. The thing about opinions is everyone has one &, unfortunately, they're entitled to have one &, sometimes, it may be different to yours...
As to the "who's at fault" question, IMO, it's not the kid being bullied, nor the bully but, in most cases, there's an underlying factor thay nobody knows of nor understands: Case in point:
My stepson was bullied in primary school. After investigating, we learned that the "bully's" father had died. Now, the kid had nothing to do with his father; barely spoke to him & didn't see him for years but, it, obviously, affected him & he started acting up. Six months later, it was all over; he even came to my stepsons birthday...
In most cases, the bully is either just trying to assert himself because he feels insecure or he's looking for attention. Of course, there's always the heroes who have to look tough in front of their mates but, again, they're usually morons...
There's an old hypothetical about "how should you react when someone pulls a gun on you?" Most peoples natural reaction is to freak out, wet themselves & beg & plead for their life. The gunman now has the power. If you go the opposite way &, inistead of begging for your life, beg the gunman to shoot you, unless you're dealing with a complete psychopath, there's a very high chance the gunman will run away thinking "what just happened?" because you took away the power by not showing fear.