I was going to ask this about becoming a costumed superhero, in reference to a couple of threads in Cafe Society. But upon some thought I realized I had to broaden the scope of the question.
Think Sarah Conner in Terminator 2. Or the protagonists in any number of horror movies like Phantasm. Or The Punisher in Marvel comics; or Batman for that matter. A former average nobody becomes sufficiently motivated (by vengence or sheer survival) to become a fanatically determined warrior. They push themselves to Olympic levels of physical fitness, learn every hand-to-hand combat skill there is, become experts with military grade weapons, and also bone up on numerous ancillary skills like surveillance, electronics, lockpicking, escape artist, computer hacking, etc. etc. etc.
My question is, is anything like this really possible? I’m skeptical because in real life there are any number of terrorist groups or militias who would love to be ultra-badasses but aren’t. I remember that when the US invaded Afghanistan and captured intelligence on Al Qaeda training methods, the conclusion was that Al Qaeda members were trained to the level of “basic competent grunts”. This was the best a fairly large and well funded organization could do? How much less could a lone would-be vigilante hope to master?