Rabbits face many dangers in their life. There are constantly things out there to get them. Dogs, cats, birds, such as hawks and eagles, foxes, and many other animals are predators to these animals.
Hundreds of wild rabbits are taken every year by humans. These rabbits are ripped away from the wild and they never truly become tame. So, if you find a baby rabbit outside, just leave it be. The mother will come back for it, she is just out getting food and water.