Don't underestimate the stubbornness of "get rich easy" people when it comes down to cheating etc. Even if it's not easy or cost effective, if this was going to be actually viral, they would tap real phones in click-farms to game the system. And do it once a year.

Why "hard to bypass" would be a sufficient thing? It depends on the technology used to connect the two phones. Bypassing this process can range from "easy" to "quite complicated", but it remains possible. Once the security is compromised, the entire network loses its core value since a single interaction is enough to establish a permanent connection.