Some people need to show dominance in their lives. There are all kinds of people who need to be the best, that drive to succeed isn’t always a bad thing if the person has the talent to back it up. In some cases, the talent isn’t there or the person in question is dealing with outside factors we don’t see, regardless that person winds up being an office bully. There isn’t one in every office, it’s not something you’d expect to see as often as you would at school but it’s not difficult to imagine a person in a position of power abusing that power.
Bullying has a profound emotional effect on everyone who’s around it. Obviously the person being bullied is the worst off but even those who witness it can be affected. It’s always advisable to speak to someone more senior under these circumstances, there’s no job or workplace where such behaviour is acceptable and as such something should be done to stamp it out as soon as possible!