Hey, like I said, I'm all for self-defense, not just as a video, or a class, but as a way of life. It's good for you physically, mentally, and the better ones work on a spiritual level too. As for confidence, I think that comes from putting the stuff into practice in the day to day, and it's more like enhanced awareness. That whole 'spy' deal of knowing - feeling almost - when someone has entered that circle around you.
I also think it's awesome for motivating people to learn how to run like hell. We began, and ended classes with the guy I studied with for 15 years by running. Part of that was strength, conditioning and getting all warmed up - but a bigger part was as Master Chu always said there were three rules for fighting on the streets. One, don't fight - RUN. Two, there is no such thing as 'a fair fight' outside of the Olympics - there are no rules. Three, if you must fight, when you put that person down, make sure they stay down no matter what you have to do to accomplish that. And that's pretty brutal stuff, stuff the average person won't/can't do for the most part.
And I just want people to be safe/safer, and I worry about too little knowledge being a dangerous thing.
Time and time again people start martial arts thinking that it will enable them to take on people bigger than them and win and what you learn in a class that has lots of real-time sparring is, more than likely, not. If I have 50lbs. on someone if I can close the distance then that 50lbs is a HUGE advantage - one your training is not likely to overcome. (Also, keep in mind that a lot of martial arts training is dedicated to overcoming pain, so even if you land a few good ones its not likely to stop me.) Much better if I have 50lbs on you that you know you could most likely outrun my fat ass. And that that is the best possible outcome.
Confidence is good (sexy in fact) so long as its kept in check, but even a touch too much leads to overconfidence and that's a killer.
And I say that because those guys who are bad, the thugs and thuglettes, the few who cause all these problems are real low-lives. I mean, not like this place here. No, I mean bad. And they grow up practicing that kind of violence, they are skilled at it, they are used to it - thrive on it in fact (it is/can be it's own super-drug) - and getting to a level where you can take them on, at their game, on their turf, is in fact, a pretty high level. Some piece of scum, human flotsam and jetsam, who is going to rape someone is going to need something more than a single Monkey Steals The Peach trick to stop them.
I've spend over 40 years now working in close proximity to highly over-agitated people awash in massive amounts of alcohol (and whatever else) and so I get to see a couple of those fights every year. And contrary to the movies and TV where people slug it out, trading punches and such, pretty much 95% of the bar fights I've seen in my life last exactly one punch. (Yeah, its one of the fun parts of the job.)
And, every now and then I also get treated to the 'Mister suburban dojo Taekwondo' putting their rule-based techniques into real life practice against some street thug, or security person, and it don't turn out so good for them. Yeah, go ahead and gimmie that Bruce Lee Walker Texas Ranger roundhouse kick, I can't wait. Because I'm (or whoever) going to catch that foot of yours up there in the air and then it's all over. Because - going back to the stuff you learn in real time sparring - the LAST thing you ever want to do is take your feet off the ground.
So the advice about taking martial arts is good, sound and solid. But it's serious stuff, and if your going to do it you have to be serious about it. And then, after years of training and practice you'll know...
You better make your face up in your favorite disguise
With your button down lips and your roller blind eyes
With your empty smile
And your hungry heart
Feel the bile rising from your guilty past
With your nerves in tatters
As the cockleshell shatters
And the hammers batter down your door
You better run