Why Disparity is good?

Some level of inequality can contribute positively to economic growth by encouraging innovation and investment. But this is usually only the case when inequality is mainly a product of market forces and is associated with aspects such as work effort, risk-taking, and investment. Too much inequality, especially if caused by factors such as inherited wealth or nepotism, can be deleterious to development.
A more specific examination is thus:
Potential Gains:
Incentives for Innovation and Investment:
When people perceive the potential for substantial gains, they will be more inclined to take risks, innovate, and invest their money. This can result in higher productivity, economic growth, and the development of new industries.
Capital Accumulation:
Increased incomes for the rich can result in more savings and investment, which can stimulate economic growth.
Effective Resource Allocation:
A degree of inequality can help channel resources towards those who are most likely to use them productively, such as entrepreneurs and those with valuable skills.
Competition and Efficiency:
Disparity can drive competition, which can lead to greater efficiency and innovation as individuals and businesses strive to outperform their rivals.

If there is no inequality then incentive towards innovation no longer exists. It also creates less education in society which does not allow people to innovate further and makes the society reliant for the lesser incentive work, creates cost savings by outsourcing work, Outsourced work receiving nation begin innovation as there is inequality, can decrease the gap between developed countries and developing countries.

Thus In order to keep a country strong there needs to be some disparity so that the country still has innovation and stays strong.