What you mean is, going on the ground is dangerous. JJJ (most JJs in fact) are not ground-focused at all. Judo, generally, focuses at least just as much on throws and sweeps as it does on the groundgame. Wrestling has takedowns too, not sure what their curriculums include though and how much of what.
Wrestling is highly focused on take downs and gaining top posistion, the take downs being more shooting like double legs, single legs, bodylock slams etc. Jiu-Jitsu is all ground game with submissions from all posistions, it utilises more sweeps and trips in its takedowns along with double legs. Judo is huge on throws. I trained wrestling and some jiu jitsu out of the grappling arts, wrestling is my favourite to be honest and I miss doing it.
But anyway, my point was that in a street fight you are best to spend as little time possible grappling as you can, because if you are grappling with someone who is resisting it is likely that you cannot see everything they are doing with your eyes, if they pull a knife out you may not see it and you will most likely get stabbed in such a situation.
Which is what I meant by saying that they are valuable skills, but aren't really the greatest for having a random street fight, because there are too many variables for you to be tied up with your opponent, if he pulls a knife or he has friends to come and help him, you will be an easy target if you are grappling with him. It's better to be able to punch hard, fast and accurate in such a situation and keep the option of retreating available if he does pull a knife or his friends want to come and help him.
@Leeshin: Judo is great but it is McBeltorama. Its 100% awesome fun and worth doing. Its great as a sport and has practical street applications.
That's not what I meant mate. There are plenty of arts where belts are used, that is normal.
What I mean is "McDojos" who are ran by liars and shitty trainers that convince people what they are teaching them is awesome, then they sell them belts and tons of other shit, making the people who are learning there think they are doing awesome, when the trainers are just in it to get easy money out of naive Bruce Lee wannabes. Then some guy who's trained there goes around telling everyone he's a blackbelt in such and such, but he actually can't fight for shit.