Some people are fortunate enough to live where they can "step off the back porch" and get their game. For them hunting is probably cheaper than buying it.
For the rest of us hunting is normally very expensive. Sometimes that's misleading because often the costs are spread over 2-3 months. My deer hunt this fall will probably run me around $400-500 once you add up food, ammo for the range and hunting, licence, travel to/from deer camp and butchering. For someone on a tight budget, they may not have the money, or would have better uses for it, especially when there's no garuntee that you'll come home with any meat.
$400 will keep the 2 of us in beef a long time.