When I was much younger, I applied for training once. At the interview I was told that they wouldn't take me on because I didn't have enough diplomas to qualify for becoming a controller, and I was overqualified for becoming an assistant controller so "I wouldn't be motivated enough in that job".
So that closed the ATC door on me forever, in my country at least.
Later, I applied to become one of a team of three ATC/airfield ops at a small regional aerodrome in Denmark. I was accepted for ATC training, but my appointment was cancelled when a Danish national applied (I am not Danish).
Now I'm just too old to be considered fit for anything except life as a consumer, a private pilot playing Airline in my own plane, at least for as long as my office job earnings are enough to pay for it. But I still remember the pain of not being allowed through that professional door.