"说到底" is a fixed idiomatic expression in Chinese formed through a verb-complement structure, where the verb "说" (shuō, to speak) is combined with the directional complement "到" (dào, to reach) and the noun "底" (dǐ, bottom). Literally meaning "to speak until reaching the bottom," it employs the concrete image of probing the deepest part of something to metaphorically convey the abstract idea of getting to the fundamental or ultimate truth of a matter after all considerations. Over time, this lexicalized phrase has grammaticized into a discourse marker, commonly used to mean "in the final analysis," "ultimately," or "when all is said and done," serving to introduce a concluding or most essential point in an argument.