Zak Bagans is a Half-Human Hybrid.His family has an affinity for the paranormal, possibly because his ancestor, Frodo Bagans bore the Ring of Power.
Something is wrong with Zak.At first, the shows have a relatively lighthearted bent and focus on the investigations and insights on what happened at the locations in question. Fast forward to season 10, and you have Zak doing things that make his very team uncomfortable, experienced paranormal investigators who know what they're getting into. Zak seems to be taking larger and larger steps away from safety, which has already cost him one friend and possibly made certain locations worse. Whatever the cause is, until it is addressed things might get worse for the GA crew.
- Based on what we see in interviews both in the show itself and the Aftershocks specials, talking about people becoming addicted to locations and their health being adversely affected (like his development of respiratory issues that require him to wear a breathing mask at certain locations unlike the others), this isn't actually all too unlikely. The thing it likely would come down to is 'how to convince Zak to stop,' considering that, as we see with many of the interview subjects, the only thing that really helps is to stop entirely, and Zak has clearly devoted his life to this.
Bobby Mackey's, the Queen Mary, Poveglia Island, the Island of Dolls and other places the GAC have investgated that have notoriously high levels of activity are all connected via wormholes.