Incorrect. The supposed MR=MC law means that the entire economy is zero-sum and wealth creation is impossible. His reasoning also directly translates to real world physical security, as in, if you want to protect wealth worth $1000 from theft, according to him you have to spend $1000-epsilon, otherwise someone is going to outspend you and steal it. Fortunately, that's not how the world works.

Visual illustration of the asymmetric security in action: https://www.pohjoiseen.fi/wp-content/uploads/2016/03/2083960...