Depends on how many people were involved in the trading. To pick a contrived example, suppose the only two transactions on the ledger were me buying 1e-9 dogecoins for $1, then you and me swapping forty dogecoins. That situation would match the circumstances you described. Kinda what this article is about actually.

on what basis should anyone believe such a ludicrous number represents legitimate skin-in-game volume and not a handful of fee-free bots trading SQL queries back and forth without ever touching a fiat ramp?

none of these self-reported volume numbers should be considered remotely realistic. exchanges have every incentive to cook their metrics in favor of "volume" to draw in fresh meat.