Does he mention this somewhere? Last time I spoke to him, he was working on Stripe Press, his interest in fraud and spam prevention long predates his work at Stripe.

Exactly. Everybody seems to be throwing around the word "optimal" but not asking "optimal to whom?".

The article was kind of long-winded so I didn't read it all. But has a catchy title. So is the title about

a) Optimal amount of fraud to the society at large?

b) Optimal amount of fraud to the businesses which suffer a loss because of it?

c) Optimal amount of fraud to the customers of such businesses?

d) Optimal amount of fraud to the chief of fraud-prevention department?

e) Optimal amount of fraud to the fraudsters?