Simple answer: the stock price. If gaming is profitable but the ads business is more profitable and less capital intensive, you would be advised to stick to ad

Simple answer: the stock price. If gaming is profitable but the ads business is more profitable and less capital intensive, you would be advised to stick to ads. Particularly when it's expensive to borrow. Reality Labs have spent $20bn already. How much does the return on that capital have to be to convince the stock market that it was a good idea?