In your example, the bid is 350K and the ask is 250K; this is not like a bid-ask spread in a regulated market, in which the bid is by definition lower than the

In your example, the bid is 350K and the ask is 250K; this is not like a bid-ask spread in a regulated market, in which the bid is by definition lower than the ask, and any bids that exceed the ask take the ask off the books at exactly the ask price. What you are describing is more like arbitrage, and it creates no value, but instead exploits inefficient markets, disparate regulatory environments, or unequal access to markets.