If you want to save the rain forest you got to make saving the rain forest more profitable than cutting it down. If its not beef, it will be the next most profitable thing which generally is corn for ethanol production, something that already has eaten a huge area of incredible nature. If not corn, it will be some form of oil. If not oil, it will be some form of rare wood to make fancy furniture for rich people.

The reason we have lost a huge area of incredible nature is not because people want to eat some steaks and burgers. It is explicitly because that land made some people money. Without that incentive the forest would still be there.