It can be quite fruitful to learn about self defense. There are many books about self defense that exist and that one can buy or borrow it seems. There are many businesses, non-profit organizations and other organizations that will teach individuals about self defense, it seems. Hopefully more individuals will learn as much as possible about self defense.
It is better to know as much as possible about self defense and to never need to use that knowledge than to not know much about self defense and need it. Ideally, peace will hopefully exist ubiquitously on Earth and a potential need for knowledge about self defense will not exist. However, until radical change happens, there exists a potential need for knowledge about self defense.
Hopefully all humans on Earth will exist peacefully with each other. Hopefully that will happen sooner rather than later. Learning about martial arts can potentially be a good way to learn about self defense. Learning about Aikido, Judo, Krav Maga and/or so forth can be good ways to learn knowledge about self defense skills, it seems. Hopefully more individuals will try practicing those aforementioned arts, systems and disciplines.
Learning about self defense can potentially be a good way to stay in shape and exercise, too. Judo practice can be a great workout. Krav Maga and Aikido practice can potentially be good ways to obtain exercise, too. Martial arts are not the only way to learn about self defense. Some organization and places offer generic self defense classes that demonstrate and teach basic skills and knowledge that relate to self defense, protecting others and personal preservation.
Hopefully all humans on Earth will learn enough knowledge about self defense so that Earth becomes a significantly more peaceful place. It seems that it will be quite good if that happens. Hopefully more individuals on Earth will learn significant amounts of knowledge related to self defense because it can be quite useful and fruit to learn about self defense, potentially.