You have completely missed the point there as well.Unlike an ATPL where if you throw enough money at it and resit enough exams most people will pass. Not just anyone can do the job of an ATCO, there is some innate ability that is very hard to spot
Not wanting to turn this thread into FC vs ATCO but I have to disagree with the above.
I have seen many people fail initial assessment and get nowhere near an ATPL course. You need very similar skills, capacity, ability to multi-task as well as good co-ordination etc. Even if you do as you say and chuck money at it until you pass nobody will hire you with the exam pass rate. 100k (of your own hard cash) not very well spend and very few if any do that.
p.s. pass rate at oxford for the assessment is about 50% i believe.