OK, then who is he? Where is there proof that you’re allowed to believe Moshiach is an abstract concept and not a physical person?
I once heard in the name of the talmidim of the gra (or talmidim of a talmid that moshiach Ben Yosef is klal yisrael in eretz yisrael and moshiach Ben Yosef doesn’t have to die if it survives past 5751