I think I may have found my answers:

6 Reasons Why People Are Bullied at Work

Targets Are Skilled Workers
You may be bullied at work because you receive a lot of positive attention for your work. Maybe you are intelligent, determined, creative, and regularly contribute new and innovative ideas. Or, maybe you go the extra mile and gain recognition for your hard work. Maybe you even move through projects quickly while others are struggling. All these things attract the attention of workplace bullies.

Workplace bullies target those that have talent because they either feel inferior or they worry that their work is being overshadowed by the other employee's work and abilities.

Bullying bosses, in particular, will target skilled workers and either steal the credit or undermine the target's work.

Targets Are Well-Liked or Popular
It is a myth that all victims of bullying are loners and outcasts with no friends or social connections. Often, it is the popular and well-liked workers that are most vulnerable to workplace bullying. If this describes you, bullies believe you pose a threat to their own popularity and social status at work.

Office mean girls, in particular, are likely to form cliques and target another woman who threatens their status or social standing. If you are well-liked at work, this could be the reason behind the attacks and jabs at you from the office bully.

Targets Are Good People
If you would describe yourself as caring, social and collaborative, this may be the reason that you are being bullied. To a workplace bully, these characteristics drain the power they have at work. Team building is the antithesis of what a bully wants. Bullies want to be in control and to call all the shots. So, you may be targeted by bullies because you are a team player.

This does not mean you should change your behavior. It simply gives you some insight into why you are being targeted. You also may be targeted for being ethical and honest. For instance, whistleblowers who expose fraudulent practices are frequently bullied by others at work to keep quiet.

Targets Are Non-Confrontational or Vulnerable
If you are introverted, anxious, or submissive, you are more likely to be bullied at work than those who are extroverted and assertive.

Research has shown that if adults work to build their self-esteem and assertiveness skills, they might diminish the likelihood that they will be targeted by workplace bullies.

There is also some evidence that depression and other stress-related conditions might attract the attention of bullies. If you are living with any of these conditions, it is important to get treatment. Talk to your healthcare provider about your symptoms. Depression, anxiety, and stress-related conditions should never be left untreated. What's more, bullying will just exacerbate your symptoms.

Article: 6 Reasons Why People Are Bullied at Work

All these reasons above are true for me.... I also happened to leak out to my former boss that I deal with anxiety - so I showed my vulnerability. And he also knows I deal with depression, because I'm sure HR told him so because HR is unprofessional.

So, I being non-confrontational and vulnerable also led to my being bullied at work by my boss AND by another former boss.