The point is, that there are a lot of people who do/did take martial arts classes, and almost nobody in situations where they are inebriated/shocked use those skills. Not to mention, the chance that the assailant has a firearm or knife is higher than you randomly walking around with one on the off chance that something bad is going to happen. Watch Penn & Teller's Bullshit, season 8 episode 3. It covers the reasons why it is mostly useless. Sure, it pumped up your ego to the point that you think you can take on 5 guys at a time, but everybody has daydreams about how they would handle a situation like that. Unfortunately in practice, when you're shocked/scared/being taken to the ground/shot/stabbed etc. you don't really have the wits or the time to think about the proper hold/hand position/fulcrum.
Sorry - martial arts for self defense are, you guessed it: Bullshit.