There was a time when I would buy books without being able to review all of the content. That stopped several years ago after buying two textbooks (one from McGraw Hill, another Pearson) that were so awful I returned them. They were both full of absolutely horrid page layouts with huge margins full of irrelevant information, just absolute garbage. I don't think they are losing money because their content is being distributed for free, but rather it just has little to no value and is not worth investment.