Trying single-handedly to topple a whole industry is really 'laughable self-miscalculation.'
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history
From 韩愈《调张籍》 (middle Tang, c. 810 CE): 蚍蜉撼大树,可笑不自量 (An ant tries to shake a great tree — laughable, not knowing its own measure). Han Yu wrote it defending the greatness of 李白 and 杜甫 against petty detractors. The image gave Chinese the idiom 蚍蜉撼树.
usage
Always the second half of the couplet 蚍蜉撼大树,可笑不自量. Reading: 量 here = liàng (to measure / assess), 4th tone. Modern usage mocks any David hopelessly underestimating Goliath.