On one hand I agree with you. It is apples-to-oranges to compare new development platform and old, second-hand, production one.
On other hand... There is NO comparable production RISC-V platforms. You say "It has 64 cores" - well, it is good argument when there is choice. But there is no choice on RISC-V side, there is no such platform with 32 or 8 or any other number of cores. So, I compare what I can buy with "RISC-V" badge and what I can buy with "amd64" badge. When I choose EPYC I could choose from 8 cores up to 64 cores, according to my wallet and needs. For 1000 euro I could have good, proven MoBo which offers more than this "development platform" (i.e. IPMI and VGA exit, which means I don't need any videocard to occupy so precious PCIe slot - and I think, it is good idea for DEVELOPMENT platform to have full remote control & access, IPMI or some other) and 8 core/16 threads first generation EPYC (which will be faster core-to-core, I'm sure), NEW. If I agree to buy second-hand hardware it will be about 550 euros (same mobo, same CPU). For 1400 euros I will get NEW 16 cores / 32 thread EPYC + mobo combo, or about 700 euros second-hand.
Yes, I know, development vs. production, but this situation stays the same for years now.
BTW, situation is the same with ARM platforms too - there is no way to buy "big desktop/small-server class" ARMv8 board with good set of expansion slot.