Because of competition between capitalists, which leads to a falling rate of profit, capitalism is structurally compelled to expand. Bigger companies undercut smaller ones and drive them out of business or swallow them up. Capitalism can never economically catch up with itself and must constantly break through its limits in a vain attempt to resolve its own inherent internal contradiction.
Capitalism will not collapse on its own. Or if it does, it will be too late to matter.
It will continue to drive down wages below what workers require to survive. It will continue to extract resources and externalize costs until the planet is made uninhabitable. It will cannibalize itself before it is fully exhausted.
We have a responsibility to destroy it that is unavoidable.