mutually assured bankruptcy 

The idea that when two hyper-competitive people or organizations decide to directly advertise against one another the firsts move will elicit a response from the second that will begin a series of escalations in marketing expenditures beyond what would be reasonable in an efficient free market to the point of bankruptcy for both people or organizations. The term comes from the Cold War-era term Mutually Assured Destruction.

McDonald's and Burger King were so concerned with market share with the Big Mac and Whopper that they lost sight of the button line and in an effort to one-up the other in marketing dollars and thus market share, they are both now doomed. It is mutually assured bankruptcy.

mutually assured bankruptcy by Fat Aaron January 13, 2020