成也萧何，败也萧何/ 成也蕭何，敗也蕭何 chéngyěxiāohébàiyěxiāohé be both one's success and one's failure
One's success and failure are both due to the same factor or person; alludes to the historical figure 萧何 xiāohé who both helped 韩信 hánxìn rise to power and later plotted his downfall.