Studying a recreational martial art of any kind is usually a game of chance in that the skills one gains might work in a self-defense situation... if one has the basic requirement which is the "Heart" for the fight. Or the Will to fight, if you prefer. Even with that being present during class time; there's no way of knowing how anyone will react to a real attack -- with or without martial training.
Experience builds ability as well as confidence; but it's also very true that mindset can change dramatically in that moment that you realized that you are not "training/playing" and that the danger is real. Some of us seem to be genetically programmed to keep fighting even while dying or being maimed; others go into shock when struck once; others surrender too easily.
More About Me
I graduated from university in the early 1970s and went on to work in a variety of fields (archaeology, Federal Government civil service and IBM Ottawa) before becoming a magazine editor with the RCMP for a decade. From 1985-1996, I was the main caregiver for my two sons while also working as a free-lance writer and teaching Chinese martial arts in the evenings.