You seem to imply that because they used Bing they couldn't still make money from ad revenue with searching. The truth is they most certainly could and probably

You seem to imply that because they used Bing they couldn't still make money from ad revenue with searching. The truth is they most certainly could and probably do (they display Google ads on their result pages). Outsourcing to Bing allowed them to, supposedly, focus on more core business related functions. Whether that was a mistake or not (or ultimately didn't matter) I don't know if we have the data to show.