BJJ as a self defence seems like a bad choice.
I think your thought of self defense is a bit skewed. Going to the ground is generally bad if you are the one getting attacked, because you are now stuck with the guy trying to hurt you.
Instead, standing up, you can always move away, run or try and get help. You can also better handle multiple opponents.
BJJ is great for law enforcement / guard jobs though, as you can subdue hostile people, and arrest them / wait for police to arrive. You can also keep criminals from escaping if you put them in a lock.
Also, some of the guard stuff seems really dangerous on concrete. I mean, actually pulling guard in a real life SD seems horrible. The guy can get picked up and slammed, get pounded with fists or get stomped by a third party.
BJJ seems awesome though, I just think you should be aware of the limitations in a SD situation.
If you mean sd as a brawl scenario, I agree the ground is the last place you want to be. If you mean sd as a robbery with some type of gun involved, I agree, the ground is the last place you want to be, but in either choice, most martial arts are worthless. In a brawl size is the most important thing probably and if guns are involved, then you are most likely fuck.
Sd in bjj is thought for a 1 v1 scenario, which is quite realistic and unlike most people think, there isn't always lava needles and friends jumping from all angles. Also the confidence given to someone that knows he can handle himself at least vs 1 person is very valuable in life in general. If you are going to get in.
Jumping guard is ridiculous in a fight, specially on concrete, the guard is that, guard! Is a defensive position that should be used as a last resort if you happened to end up on the bottom, the idea is to be on top. Getting slammed is quite possible, that's why I don't like armbars, triangles well done are not slammed prone, you can prevent the slam quite easily.
Getting punch on the face, well that's why we train guard and control positions, so you don't get ktfo while in guard. Friends of your enemy jumping in? Well, don't be an idiot and pick a fight vs multiple opponents, whether on the ground or standing, if you are outnumber by some dudes with mean intentions,ya you better have your friends to back you up, id not, then your probably fucked.