>>22870666It's because capitalism cannot really care about the environment, it's an externality to the market. The profit motive will always prioritize that which generates more short-term growth even if it's unsustainable, rather than a business model which prioritizes long-term stability and viability.
The capitalist who cuts corners and doesn't care about regulations and the environment, just getting the numbers to go up no matter what, will always out-compete the "good" capitalist who cares about the environment and has more sustainable business practices.
The market economy, governed by the profit motive, has its own logic; its own laws. And the long-term existence and prosperity of humanity doesn't factor into that. Why care about what happens hundreds of years in the future when you can just get rich now? The vast majority of people do not have a say. There's de-jure democracy in most capitalist countries, but money overrides that and representatives usually reflect the will of their donors and rich lobbyists rather than their actual constituents.
Communism on the other hand doesn't have a market economy or the profit motive. Production, distribution, and exchange is done on the basis of a plan which is meant to meet people's needs. The profit motive wouldn't exist under such a system because the market economy would be replaced with a planned economy which would be both willing and able to deal with the long-term challenges that humanity faces in its development.