When you fly into Terrance B. Lettsome International Airport on Beef Island, your home phone plan switches to roaming. That is where the money problem starts. Mobile data in the British Virgin Islands is some of the priciest in the region, and most roaming plans charge you at least ten times what a local carrier charges. A few days of normal map and chat use can turn into a shock bill.
There is no SIM stand at the airport either. To get a local SIM you have to travel into Road Town on Tortola and visit a Digicel or Flow store during opening hours. That eats into your first day. A MegaEsim eSIM skips all of that. You buy it before you fly, install it at home, and it connects to the Digicel network as soon as you arrive.