Do I need ETH on arbitrum?

Excuse me, could you possibly explain to me the necessity of holding ETH on Arbitrum? I'm a bit confused about its significance in this ecosystem. Would it be beneficial for me to have ETH on Arbitrum, and if so, why? Could you elaborate on the potential advantages it might offer, or are there any specific reasons why I should consider this? Your insights would be greatly appreciated as I'm trying to make an informed decision about my cryptocurrency holdings.