The software is freely replicable, the hardware is not. And the hardware for just the “running the AI” part of the reusable AI fighter is going to be more expensive than the electronics of a single use fire-and-forget air-to-air missile, and so will most of the parts of the fighter compared to the missile.
You don’t need a 1.8T parameter LLM to control an AI guided missile. In all likelihood, the model to control these can be run on an iPhone-level computer, which is max $1000. The bottleneck is still the missile.