It's not useless, although better self-defence systems exist.
Generally speaking, most combat sports aren't ideal for self-defence because they have restrictions on where and how to strike, as well as they tend to focus on not ending the fight immediately.
Self-defence ideally should focus much more on ending fights as quickly as possible.
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“Anyone who wants to thwart the establishment of a Palestinian state has to support bolstering Hamas and transferring money to Hamas, this is part of our strategy” —Netanyahu戦争ではなく戦争と戦う
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