Actually, I can't remember a sigle case of someone who didn't make it, even the worst cases of antisocial, alcoholic, borderline guys I have dealt with got their licenses.
I know ONE. A single one who trained with me, very reputable FAA flight school, family-run business, far away from all the "pilot mills".
This chap did some hour building, was totally untalented and barely spoke English. Only flew in uncontrolled airspace because he wouldn't understand ATCOs, turned the avionics master off and on in flight because he couldn't hear anything in his headphones (he plugged it out accidently
), etc.
Head of flight school told him he does not want his business and let him go because he should never be a commercial pilot (what he wanted to train for). Major props to him for not taking the money.
Then again, probably some other school picked him up and he's got a CPL by now
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Unfortunately I agree on the smoking hole in the ground thing.
People ONLY EVER learn if things go wrong beforehand.