Up & Away, it wasn't empty until I took up rotary! Mind you, I wouldn't change a thing if I had my time again- except I would start earlier.
The point about some people being unsuitable for helicopters came from a 15,000+ hour instructor/test pilot who is well known in the light helicopter world. No one knows what the percentage is until we put all of the population through a PPL but from my very very short time in the industry I would guess around 5-10%.
The bell curve gets a bit flat towards the bottom end...