I’m not saying this to brag, just to give background.
I teach Judo and have a background of 15 years of Karate and Muay Thai.
Judo is a sport, as is Muay Thai.
They are fun, will get you fit, make you mentally and physically tougher and have lots of techniques you can carry over into street brawling.
It’s not just about techniques though. Your mentality, the other guys mentality, weapons, numbers and sheer bloody luck all factor in just as much.
Take a martial art if you want, just don’t kid yourself on that it’s turning you into the ultimate street warrior.
In the 15 to 1 scenario the OP posted, theres no way I’d be hanging around trying to face any of that lot down. How did the event develop anyway? Did 15 guys just decide they were having you or had there been a bit of verbal going on?