"I fear not the man who has practiced 10,000 kicks once, but I fear the man who has practiced one kick 10,000 times"

In this quote, Bruce Lee is emphasizing the significance of devotion and proficiency in any skill or craft. He is stating that it is not the amount of practice that matters, but rather the quality and depth of that practice. A person who has actually practiced one kick 10,000 times has likely refined and perfected that kick to a high level of ability and precision. On the other hand, an individual who has practiced 10,000 different kicks may not have the exact same level of proficiency in any one kick. Therefore, Lee is cautioning against undervaluing somebody who has actually devoted themselves to refining one ability, as they might be more formidable than somebody who has a superficial understanding of lots of abilities.