What is phishing success?

In putting together awareness programs for dozens of clients, the potential to integrate phishing simulations always comes up. For the most part, it seems like a staple of awareness programs. But when the concept of phishing is raised, I always ask, “Why?”
Yes, the question potentially costs me money. Also while most people perceive the phishing simulations as a direct way to decrease phishing susceptibility, the decrease might not be relevant or significant. So when I looked at a r