When I make ground venison I add pork or beef fat to the mix. If it is made without the fat, when cooked as burgers they are to dry to eat, and the fat adds flavor. How much to put in is a personal choice.
We have such an abundance of food now people can pick and choose what animals to eat and what parts of the animal to eat, selecting “healthy diets”. When food is in short supply all food is healthy, and the more calories available the better it is for you.