It's not speculators, it's groups exporting to china where they're moving the chips to new cards for use in data centers. [0][1]

Probably related, china banned imports of the 5090d in may.

- https://videocardz.com/newz/heres-why-rtx-5090-costs-5000-ai...

- https://videocardz.com/newz/inside-chinas-mass-conversion-of...