I can think of a few reasons TTT.
They may have booked their holiday before Covid was even a thing, and if the Govt is still allowing travel, and their travel company hasn't cancelled, then it's a case of use it or lose it (if you'd spent, e.g, £5k on a holiday, would you not go? I know damn well I would go).
They may go to escape Covid! There's plenty of places that are significantly safer than the UK, and the UK is very bloody safe from the risk of dying from Covid to the point of statistically irrelevant now.
They may have booked their holiday when the Govt opened the air bridges - by dint of which the Govt were saying it's fine to go on holiday.
There you go, there's three perfectly legitimate, and in no way desperate, reasons for you to consider.