In my opinion, airshow accidents are highly regrettable, but also will occur for as long as we have airshows.
Bit blasé that - collateral damage?
Airshow accidents could be greatly reduced if the pilots displaying performed no aerobatics that had any risk i.e. used the display to 'display' rather than show off.
Few people watching appreciate the difficulty levels of some of the aerobatic manoeuvres thus they are best avoided.