What goes up must come down. That's not always a simple, safe exercise; we only know for certain that the up/down is a necessary sequence of anything that leaves the ground with the intent that it return to the ground safe and secure.
That it sometimes does not return safe and secure is what makes the result tragic. In the case of Prime Air, it was the landing that failed; all deaths [5, at present] occuurred with the plane already on the ground. How to stop tragedy? Well, like banning guns, such action will not eliminate death from ocurring by banning flight. Going up in the air by rebound from a trampoline can and does have tragic result. Is the air too dangerous? Or the trampoline. Not oftren enought to ban them.
The NTSB activity has resulted in new tech to resolve some recurring problems. As a result, it is demonstrated that we are now safer boarding an aircraft, flying in it, and returning to the ground in frequent, safe occasions that makes airline travel one of the safest, secure modes of travel for people and for goods.
Peole are fallible; always have been, always will be.