“Income inequality” is just a feature of a power law or logarithmic distribution of income.
Steven Keen explains this here:
Income correlates with positively well-being, other variables being the same. But there is no inherent reason why a high quality “standard of living” isn’t possible with low levels of consumption.
You suggested that “poverty” may offer a solution to this problem. I have thought about this possibility myself at times. If people can’t afford much consumption, it would reduce their environmental impact!
I would much rather see people consuming less willfully, both because they understand the impact of consumption, and because it’s better and easier to live a laid back, minimal lifestyle.
If people are forced into poverty and resource deprivation, it can make them desperate and competitive. This leads to a temporary or conditional reduction in consumption. Once their incomes increase, the effect disappears, or even backfires. However, if they change their habits because they realize there is a better way to live, the effect is deeper and more permanent.
Income is one dimension of social/political influence. It is a symbol we create to make decisions collectively. We give some people power to tell us what to do, while others we push to the margins, and force them to live a precarious existence.
A major issue is that our collective focus has been on colonization and domination. This allows us to organize and control resources. We can build amazing things and huge systems/societies this way. Our civilization has realized empires on a unprecedented scale(However, being unprecedented actually has a long precedent. Each new society does something new)
It is impossible to evaluate “overpopulation” without describing the political context in which the “populace” lives.
Our political paradigm is unsustainable, that much is clear. This was the case long before Donald Trump became the president of the United States. The pattern of domination, exploitation, and coercion will break down. And the way we use resources reflects a lack of understanding of our position. Humanity is desperate and confused.
Without these systems of control, our populace could not be supported. With them, our attitudes and actions are often violent, despicable, or wasteful. What is to be done?
Perhaps we can re-institute a society of cooperation, in place of the politics of domination. I think we have a chance.
Most other suggestions either ignore how the growth of our population has made us incredibly interdependent, or the limits of the ability of our ecosystem to support human activity.