At first, I wanted to study Brazilian Jiu-Jitsu so that I could do all of the cool submissions which I saw in the UFC. Not to mention that choking an assailant unconscious seemed much more humane to me than breaking their ribs and knees with my front kick. That being said, I came to realize that there would be three drawbacks to making subs the focus of my BJJ training.
1) I'm a muscular man in his twenties. Very few people will be stupid enough to attack me alone. If I get Gary the Gangsta in a kimura from the guard, what's to stop his homeboys from soccer-kicking my head into oblivion?
2) If someone does attack me one-on-one, they will probably be armed. For that reason, going for a triangle choke against a guy with a switchblade or a pistol sounds like a funeral in the making.
3) There are many ways to get out of a submission hold which are barred from the cage. For example, what's to stop a street fighter from going "Golden Corral" on my arm when I go for that rear naked choke? Biting may not be an honorable way of fighting, but violent criminals aren't known for their honor. They're known for jacking people up, and that can involve eye-gouging, ripping off your nuts (if you're a dude), attacking "above the belt" (if you're a girl) or worse!
So while I will still learn the submission holds, they will not be my focus. Instead, I am going to master the sweeps, a.k.a. the art of getting the heck back up! That way, I can hightail it out of there before I get a fatal beatdown from a bunch of teenage gangbangers. I'll also be in a better position to disarm my attacker before they cut me to ribbons or put a bullet in my butt. Not to mention that I will be able to avoid the biting, eye-gouging, throat-grabbing scramble that a real fight on the ground usually turns into. And that, my friends, is the real value of BJJ: it teaches you how to escape with your life!