I am explaining to you and the others as well who will read this. Maybe the opponent queen is weak or overloaded or doesn't have a defense or counterattack. Maybe our passed pawn will promote and give material advantage to us.
This still doesn't make any sense at all.
Maybe your pawn won't promote after all. Maybe you will get checkmated before the pawn promotes. Even if it promotes (which is a big "if"), it will be a queen, not more than a queen.
For example, there is a rook, a king, 2 passed pawns vs a king, queen and an undeveloped pawn. In this case, both of them will overload the opponent queen. One of our pawns will promote. Then, exchange and material advantage.