https://www.businessinsider.com/business-insiders-top-advertising-and-media-stories-for-september-8-2020-9
AT&T undervalued the importance of "search", the company decided to focus more on becoming a media giant at all cost.
The decision to focus more on media meant they neglected consumers, trends and a need to improve the user experience. AT&T managed to screwed up the loyal customer base in a massive number as their viewers started abandoning ship.
AT&T's content Aspirations failed to make enough of a profit in order to scale. The question becomes "Will 5G will be able to carry this company as a whole?"