I suggest to reframe: Criticism contains an opportunity to learn! Submit a paper and be curious (not scared) about the comments of the reviewers - there you will have an expert opinion, maybe even receive concrete advice on how to improve on your work. I have had more than one occasion that a reviewer directed me to methodological or theoretical literature which helped me grow. Create an image in which you see publishing not so much linked with bravery but with the openness for new ideas and the readiness to ask for constructive feedback.
I would say, until and unless somebody is sponsoring a bravery award for publishing the articles, bravery is not a necessary factor at all. If you have accomplished your research work in a bias less, non-plagiarised way and if you send it to the right journal that suits your research topic, it is sure to get published. Where does the fear factor comes here?
Confidence and knowledge is necessary to publish papers and confidence comes from being sure about oneself and that needs a person to be brave and with total acceptance of oneself and one's strengths and weaknesses. Thus,logically bravery is necessary to publish and , I believe, brave publish more !
In my opinion, bravery and confidence go together. This traits are more visible when the researcher publishes against widely held beliefs or on contentious issues. Such works may be seen as self serving irrespective of its quality. History is a witness of such works which gained positive recognition many years after the death of the researcher.