ATC_intrain, the <10% plucked percentage is drawn from a rough 50% success rate - passing the course and successfully rating, and assuming at least 10:1 rejected:successful applicant. More addressed at burning your bridges than answering the chances of being selected, but then overall outcome is something to consider.
I'm surrounded by controllers who have come to ATC not because that's all they wanted to do since they were a lad/lass, but because after doing something else they thought it might be interesting & they might be suited. Enthusiams & desire can only make up so much for a lack of aptitude.
Good luck. We need every bum in a seat we can get rated.