Safety and proficiency come at the same price with firearms as with any human endeavor: Practice, practice, practice.
The researchers determined that while those efforts mitigate the physical, legal and moral risks associated with using handguns for self-defense, it does not remove all risk.
Nothing is risk free.
A smart person does what seems to be the best for the situation at hand. If it is walking across the street, riding a bike, driving a vehicle to defending oneself.