A post here last year was lamenting how they pulled the plug early on a startup because OP had run the numbers to find they were paying something like $5 per si

A post here last year was lamenting how they pulled the plug early on a startup because OP had run the numbers to find they were paying something like $5 per signup but only making $2.5 per user. The whole post all I could think was, "are there really people that depend only on advertising for new users?"