TJ and others, the hazard is the drop (or other obstacle), the risk is the chance of going over it, and the severity relates to the height of the drop and the consequences of an accident.
The risk may be reduced by signage and trail design, rider skill and training, and use of the correct equipment, the severity by armour, helmet or crash padding/nets. In the end, we all make the judgement whether it the risk is worth it for us each time we ride wherever we ride.
My condolences to family and friends.