I don't see how this makes the economy inefficient. Could you elaborate? Deals are supposed to create value. For example, if a house is worth $2M to the seller

I don't see how this makes the economy inefficient. Could you elaborate? Deals are supposed to create value. For example, if a house is worth $2M to the seller and $3M to the buyer, there's $1M potential surplus to be captured. A deal at $2.5M makes that makes that surplus real, in effect giving $500K to each. If a potential deal doesn't create net value - if the buyer doesn't receive enough benefit from the good, or the seller spends too much manufacturing it - the total wealth in the economy goes down as a result, even though the buyer OR the seller might win personally. Serendipity happens. Yes, and statistics can tell us what credence to assign to the chance of it happening. I certainly see no reason to assign 50% or similar credence to serendipity in the described case, or indeed any credence high enough to dominate the certain loss of value. Do you?