The US car industry.
Ford, Chrysler, GM. They became complacent. They sold shitty cars, with shitty reliability for slightly inflated prices with no care for the consumer. They just wanted sales. And slowly, the Japanese and German car manufacturers took over the market with quality and reliability. The end result is well known. All three went through bankruptcy, Ford a few years before GM and Chrysler did so. And now? Even years past that time, the "big" three are in the shadow of Toyota, Honda, and VW. GM only sells as much as they do thanks to China.