Have you included the PCB design too?
That's only the imaginary chips IP cost. PCB design costs are way, way lower. If you released the chip specs under public domain on tapeout's day you would probably get a few independent community designs + the ones you paid for ready for when you have the chips in hand.
Yes, but the total cost for PCB design and/or the components for 5k miners should add more than 1M$. I am sure that you are aware that ordering LOTS of components needs upfront money and a lead time.