[crc32]

"unless you bring some value to the game that the new guy can't." yes, like the supply of a scarce resource. This little get out clause renders your argument meaningless.

If there are only 100 tons of gold available per week, (the marginal cost of producing the 101st item is infinite, i.e. non-zero) it does not matter how many competitors there are in the market. If demand is for more than 100 tons, profit margins will not "tend to zero". This scenario illustrates that even in a commodities market a situation may arise where a large number of competitors will not cause margins to tend to zero.

Let alone situations where branding is involved etc. - all factors that we can assume are permissable under the stated condition of an "open market", and all in the category of "some value to the game that the new guy can't". So in other words your comment amounts to "yes it does, except where it doesn't"

[mseebach]

You're confusing profit from speculation and profit from value added sales.

Especially in the gold-market, profits come from speculation, not value added sales.

[crc32]

No, I contend that it is you who is confused. There is only one type of profit, and I am correct that profit may be derived from demand exceeding supply irrespective of the number of suppliers. This has nothing to do with speculation, it is a basic concept of market economics that holds true in an "open market" as defined by the original commenter.