I’m speaking about born again Christians who know they need immersion after conversion. I don’t believe most of the protestant churches think it’s salvific like Catholics do. I’m willing to bet most Protestants just think it’s a good thing to do, not that their child’s salvation depends on it.
However, you still overlook the FACT that MOST Protestants who are baptized as infants are never baptized again.
As far as whether or not Protestants view the Sacrament of Baptism as salvic, I don’t know and I’m not sure I care. In the past five centuries, Protestants have distorted, minimized or destroyed ALL of the Sacraments (not long ago we could at least take comfort in knowing that they had left Marriage alone, but that is no longer the case).