Capitalism means always looking for more profits. Endless efforts of private owners to expand and increase their profits leads to the perpetual circle of suproduction and overconsumption which destroy ressources and ecosystems.
This particular system is the main reason it's happening.
A socialist or communist society could be healthier. Not saying it automatically would be. The only people theorizing a sustainable economy are on the (far) left though.
And the last 50 years proved that sustainability is impossible in a capitalist system. It hinders profits, and the basis of capitalism is: always more profits.