Word population is 7.7 billion people. How did it reach such a number? Capitalism gave us the capability to grow and distribute food and incentive to invest huge sums to give us modern medicine to reduce large scale disease. Wars are now small with low body counts.
The solution to the problem you describe is large scale nuclear war. Kill off about 7 billion people and we won’t need capitalism to sustain the huge population. Nuclear winter will take care of global warming.
If people are there Earth’s problem, massive depopulation is the solution you seek. Bring back war, famine and pestilence. Where is Stalin when you need him?