I think you might be two orders of magnitude off here. A class leading general purpose compute chip on a cutting edge process? I don’t think $5 billion to produce working chips is unreasonable. If it were only $50M to produce A14/M1 level chips, Qualcomm would already have done so.
Cerebras is cool, but they are not on TSMC 5nm and don’t have to design general purpose silicon, where you have pesky things like huge reorder buffers or 8-wide decode blocks, which are not seen in any other production CPU right now.