Like any other competitive activity, RedHelenB, maths can be done with varying degrees of seriousness. Taking it more seriously usually leads to better results - not only in this competition, but in future maths contexts. Some of us think that's a good thing! When people make a virtue of not preparing for UKMT competitions I'm reminded of the Flanders & Swann song:
"And all the world over, each nation's the same
They've simply no notion of playing the game
They argue with umpires, they cheer when they've won
And they practice beforehand which ruins the fun!"
The UK team just did very well, and came top of Europe, in the International Mathematical Olympiad, with three gold medals, two bronze and an Honorable Mention. You'd better believe those young people prepared, and the JMC is, for some, the start of that road. The IMO in turn is often the start of stellar careers: eg Maryam Mirzakhani, the Fields Medallist who has tragically just died, started that way.