Because that ship has sailed, and the constitutional process was followed to make Biden the POTUS. There are exactly 4 paths to change the President - death, resignation, 25th Amendment, and impeachment. In all cases, Harris becomes POTUS. Anyone spouting some other hopium is full of crap.
Wrong. The Constitution says that the president must be elected. Bitem was not elected legally, the election was stolen. Harris is a dual US/Jamaican citizen so she's not eligible, plus she's only in the position because of a stolen election. You're an angry defeatist.