Scientifically it has been shown that stings of hornets are not more dangerous than bees and wasps. Those striking out in fear are those that may be stung. For most people a hornet sting represents no special danger. Bees are nectar collecting animals, but wasps and hornets are hunters of insect prey. With several kilograms of honey in an average bees nest, the primary role of the bee sting is to defend the colony against sweet-toothed attackers, ranging from the mouse through badgers to brown bears and humans.
Wasps have substantially fewer such natural enemies.
This explains the autotomous sting of the honey bee, a bee will lose its sting and its life stinging a vertebrate. What it gains is the injection of additional poison from the poison gland which continues to pump on its release, injecting about 0.1 mg of toxin. Wasps and hornets use their sting to kill troublesome insect prey. They cannot afford to be wasteful, as they need to be able to sting repeatedly, injecting just 0.01 mg. In exceptional cases hornet stings, like other insect stings, can induce an allergic reaction, arising from an overactive immune system.