Think Chuck said it all.
The maneuver itself is not dangerous if you know what you're doing. But the pilots are pushing the limits and it takes less and less "unexpected" to cause a crash. And next time some other pilot will try better... that's the danger.
It's more difficult to say "stop" when reaching the limits, then to continue to prove something can be done on that tiny edge. The first type of guys are pilots, the latter are cowboys. These pilots are cowboys cause they like to proove they can work on the edge. Why turn so low?
We're all pilots, I'm sure 90% of us would be able to fly like this. Unfortunately some would like to show it to the public to...