So, you propose that they either enrol in 10 different martial art classes or they don't do anything at all. Sorry, but we have a life outside the dojo, we are not samurais...
Arno, you've clearly got an axe to grind, so I'm not sure why I'm bothering, but here goes. What you just did is a combination of a strawman argument (misrepresenting the position of the other side in order to make it an easy target to destroy with great drama, rolling of eyes and clutching of pearls..."Sorry, but we have a life outside the dojo...") and a false dichotomy. You've constructed the absurd position that the choices for self-defense are 1)taking ten different martial arts classes or 2)doing nothing, and then attributed that position to me. This is intellectually dishonest, and quite laughably so.
You say you want a solution, yet you refuse to define the problem. How can you expect useful answers if that's the approach you take? Do you walk into a hardware store and say, "I want the best tool in the store", refuse to answer when they ask you want you want to use it for, and then yell, "So you propose that I either buy every tool in the store, or not buy any tool at all!"? "Self-defense" is the same. Who or what are you defending against? Why are they attacking you? Where are they attacking you? Do they have any skills, weapons, other resources? Is this a movie-fantasy attack in the stereotypical dark alley, or is it something more realistic, like an attack by a spouse or partner? Et bloody cetera.
No one can help you if you refuse to frame the problem in terms that have some relation to the real world. If you'd rather just move the goalposts every time someone tries to give you an answer, so you can have the satisfaction of ridiculing their response, then I wish you every bit of the rancid, bitter enjoyment that kind of game brings. Meanwhile I'll be over here investing in circus pony futures.