Why would anyone want to put themselves through the mincer at CATC when they don't want to be an ATCO?
Be under no illusions about the college; it's two strikes and you're out, you are forced to study at their pace - not yours, and there is a very high workload throughout the course. Hence the high failure rate.
Also, there's the constant threat that an uncharacteristic mistake on the day could get you chopped - something I'd certainly not had to deal with before CATC. Often people are already on their second go - and that's it: game over. It happens to the best of 'em, but that's the nature of ATC! No second chances in the real world.....