My conclusion is that many of those who act in a bullying or antisocial manner are negative attention seeking.

Everyone needs attention. It's a human trait to seek attention. More or less attention depending upon the individual, but the need is always there.

Ideally, people learn how to garner attention through positive routes. These can include friendships, helping others, awards, competition, sports, or music/theater performance. As children and growing up, we learn strategies to get attention. This is hopefully guided by our parents, authority figures, friends, and society to teach you ways to get attention in a positive and socially acceptable manner, with the best forms helping other people in the process.

Unfortunately, not everyone either gets that formative training or just never understands. I thinks it's more the former than the latter (instead discussion of sociopaths and psychopathy here). Many of the kids that I've been around who have bulling mentalities responded very well to an authority figure first standing them down, then working on attention positive strategies. They often just didn't have the tools to integrate in a group without bullying to be seen. I'm not a trained social/psychologist professional, but I've worked with a lot of kids over the years, and this approach has worked the vast majority of the time.

Adults who never figured out how to get positive attention seek negative attention. That loud muffler? It's about demanding attention. The yelling in a restaurant? Attention. They are frustrated at the world sometimes because people don't give them attention and one of their only tools in their toolbox to get attention is to be annoying because negative reactions are still reactions.

I pity those people. That's a sad life. It makes for bad transactional style friendships, hateful marriages, and leaves them ill equipped to raise children that will have positive tools in their own lives. If their children do figure out how to be positive in communities, that should also help them to see how their parents are toxic, so it's a no win for the parent in that scenario.

There's, of course, always exceptions such has narcissistic traits, sociopaths, and other mental illnesses, but for most people looking at their behaviors through a lens of attention seeking frameworks fits well enough. Trolls online are to be pitied because they're sad and want attention, but don't know how to get it without bullying and trolling in life.