How do you know it came on suddenly? The article says:

Within two years of beginning to take the drug the married father-of-two says he developed an uncontrollable passion for gay sex and gambling - at one point even selling his children’s toys to fund his addiction.

“Within two years” implies that it developed over this time frame. That’s anything but sudden, especially since it most likely started off with sporadic impulses and got more intense over time - how addictions usually go.