Very few, fortunately. But what matters is the physical and psychological forging this kind of training provides.
Why does that matter? Yes, we can all agree that physical fitness and mental toughness are good things, but exactly what is the crossover of "ability to succeed at fighting" to other aspects of life? Why is fighting better preparation than competitive activities generally, or "standard" aikido training? I wouldn't say that professional fighters are particularly noted for their life skills...