I worked as a Krav Maga Instructor for around 2 years. It has it's place as a military combative. It's quick and easy to learn and gives you a pretty good one.

The problem is it's marketed by most people as some magic bullet solution that'll turn you into Jason Bourne in 6 months. Wrong. So, so wrong.

Let's take knife attacks. Krav Maga makes pretty big talk about it's utility in defending against a knife. Let's look at the Israeli Defense force as an example. Everyone there has had at least a year of high quality Krav Maga training. On patrols in Gaza on of the most common problems have now is random stabbings. A random person will come up pretending to ask for help or to get their papers checked and then go mental with a knife and try to stab and slash at as many people as possible.

Not only do civilians get stabbed, but armed guards get stabbed too. It's one of the most frequent kinds of attack because it's so damn effective, and everyone in Israel is taught Krav Maga. So you can say this much. Knowing Krav Maga will not reliably stop a knife attack.

The exact same thing goes for fighting 3-4 people. There's so many different factors, relative size, space, exits, incidental weapons etc that would have to be working in your favour before kill even comes into the picture. Now if you're a Brock Lesnar looking dude and 4 unarmed guys try to fight you in an empty alleyway by a main road. You'll probably get out just fine. Stick the same guy in the middle of a pool hall and the odds drop drastically. You can be fighting 3 guys pretty well, which is practically impossible on it's own, while the fourth goes and smashes the side of your knee in with a pool cue of glasses you over the back of your head. Cue serious injury and getting your face collectively kicked of.

The thing is Krav Maga teachers aren't stupid. They know in that situation a guy with no military training or fight training would be fucked, and best case scenario is not winning, but getting the fuck out of there. Thing is, that's not how they market it. It's the main reason I wouldn't teach it now. It's irresponsible and could give someone a false sense of confidence that'll get them killed.

If you want to become a competent fighter, learn some MMA, or just boxing and wrestling if you dont fancy that. But if you want to feel like you can beat up multiple people and stop armed attacks with your bear hands, save yourself some money and just go buy a power ranger costume.