Custom state-of-the-art silicon is ridiculously expensive.

For a minimum 100 wafers = 10k chips, Groq may have paid $100M = $10k/chip purely in amortizing design costs.

Chip design (software + engineer time) and fabrication setup (lithography masks) grow exponentially [1][2] with smaller nodes, e.g., maybe $100M for Groq's current 14nm chips to ~$500M for their planned 4nm tapeout. Once you reach mass production (>>1000 wafers, which have ~150 large chips each), wafers are $10k each. On top of this, it takes ~1 year to design then have prototypes made. (These same issues still exist on older slower nodes, albeit not as bad.)

This could be reduced somewhat if chip design software were cheaper and margins were lower, but maybe 20% of this cost is due to fundamental manufacturing difficulty.

(disclosure: I don't work with recent tech nodes myself; this is my best guess)

[1] https://www.semianalysis.com/p/the-dark-side-of-the-semicond... [2] https://www.extremetech.com/computing/272096-3nm-process-nod...