Because the value of most of the things you needed to buy (mostly other people's labors in food service, etc.) was cut in half too. Of course this doesn't count imports (which became twice as expensive in real terms) but that's a hit that can actually be survived.

The value of their paychecks probably remained about constant for local goods such as food and rent. They probably fell a lot in terms of things like flying to London to go shopping and that is a real change but probably one they can live.

It's really the value of their paychecks relative to imports. (In a small country, you do have to export a lot relative to GDP, but you can wind up exporting cheaper too)