Recently I watched again Bruce Lee's Long Island Demonstrations in Youtube. As I see it, Bruce Lee was more with a street fighting style than tournament style. Therefore his sparring demonstration looked rather "basic" when compared with today's professional MMA fights (but as veteran MMA fighter Bas Rutten once said something like should Bruce be around, he should be able to pick up the new MMA tricks in no time). His other demonstrations however did show some good insights into street self-defense.
Bruce demonstrated his famous "unstoppable punch" showing his speed in closing his distance between him and his opponent and he was able to land a really quick punch to his opponent's face! In ring combat, landing a quick punch is only part of the story, the punch must have power too! Not so in street self defense where there is no hold-barred.
To complement his "unstoppable punch", Bruce also demonstrated his two finger push up. One can imagine the power of combining his fingers strike (to where you guess!) with his "unstoppable punch"!
The most famous demonstration of Bruce is however none of the above, but his "inch-punch", by which he can deliver a powerful punch with his fist close to or even touching his opponent's body. Again, this is not a ring-combat technique. In today's professional MMA fights, this will be the grappling range; and a seasoned grappler won't allow his opponent to execute such a close range punch without grappling him and destabilizing him.
Can inch-punch be executed in street self-defense? In street self-defense, unless he is a trained grappler who can quickly throw his opponent to the ground, the defender will be better advised to avoid being grappled. With arm-sensitivity training (such as pushing hands or sticky hands), a practitioner is trained to punch or throw his opponent before being grappled. Bruce's inch-punch fits into this strategy of self-defense. In situations where one's opponent is not a seasoned grappler, this strategy does make some sense.
In summary, the strategy of street self defense can be summarized as follows: avoid being grappled, avoid being punched (or kicked etc), do speedy attack to the opponent's most vulnerable part, and finally, get away from the situation at the earliest possible opportunity.
Final question: Why should a peace loving person train for self defense in a safe city? Answer: Objective of training for self-defense - A well-prepared man is a more confident man, no matter whether or not he will encounter such situation ever in his life. And a more confident man will be more ready to protect his own rights and/or the rights of his weaker neighbors - including in situations where "physical solution" is not called for.
Bruce Lee's Long Beach demonstrations: