成也萧何，败也萧何 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|蕭何|xiao1 he2]] who both helped [[韩信|韓信|han2 xin4]] rise to power and later plotted his downfall.