Actually, Yusuf Zuck understood Jerome Hart and the others very well. They were young, alone in the world, with no entanglements, so wherever they went felt like home. Moreover, young people are naturally imbued with a spirit of adventure, and the allure of a magical, unknown world was tremendous.
Even Yusuf Zuck himself would have entered without hesitation if not for his many commitments. Unfortunately, it wasn't an option for him; if he left, who would take care of his home? And he definitely wouldn't take his whole family on an adventure.
The island was very safe, patrolled by boats, guarded by the most powerful Skeward Security team, and even the Dogan couple, Sophia, and two helicopters on standby at all times. Should any expert set foot on the island, the security team would whisk the VIPs away immediately.