Because snake venom is bitter and hot. Snakes have no bones, feed on grass growing in the soil, and occasionally eat residual birds or carrion. Snakes are muscle-building animals, which are eaten by human beings and have a good effect of reducing fat and slimming. But eating more is not easy at all. Snake meat is oxygen-free, which will erode human hemoglobin and reduce oxygen flow. With the fetus, the female snake itself is a bitter body. Compared with other vertebrates, the density of spinal canal is smaller.

This is also the reason why snakes are not too big.