During WW2, the Allies wanted to armor their planes better so more would survive missions. But armor is expensive and heavy so you’d have to prioritize where to put it.
So they go out and collect data on the returning planes to see where they’d been hit. That picture is basically the data collected: where returning planes had sustained the most damage.
So most of the engineers looked at that and went “Aha, the points with the most damage should be armored, since they get shredded up pretty good.”
And one engineer went “Um actually, if they got shot there and came back, armor doesn’t matter. We need to armor the spots with no bullet holes, since a plane shot there wasn’t able to return.”
And so it was, and they called it Survivor Bias.
In this case, it’s survivor bias about becoming more conservative as you age