The nature of air warfare means we need a lot.
Not enough pilots means the US doesn’t rapidly acquire air supremacy in any conflict. Without air supremacy, a lot more people die and war descends into combined arms attrition and protracted engagements.
It takes a lot of planes to achieve true air supremacy. Drones can’t do it yet. Every hour that goes by with contested skis means pilot losses in a real war. Having fewer pilots means you lose more pilots.