The concept that "the rich get richer" refers to the idea that those who already have substantial wealth have the means, knowledge, and opportunities to accumulate wealth at a faster pace than those who do not. Several mechanisms and factors contribute to this phenomenon:

1. Compound Interest: This is a fundamental principle of investing. Money that is invested earns interest or returns, and this interest earns its own interest over time. As a result, the total amount can grow exponentially. Those who already have substantial amounts to invest can thus accumulate wealth more quickly than those starting with smaller amounts.

2. Access to Better Investment Opportunities: High net-worth individuals and institutions often have access to better investment opportunities, advisors, and financial instruments that are not available to the average person. They can also diversify their investments more easily, which can lead to better risk-adjusted returns.

3. Economies of Scale: Larger businesses or wealthy individuals can take advantage of bulk purchasing, better negotiation power, and other economies of scale which can increase profitability and wealth accumulation.

4. Leverage and Other Financial Tools: Wealthy individuals and businesses can use debt and other financial instruments in strategic ways to magnify their returns.

5. Education and Knowledge: Wealthier families often have access to better educational resources, tutors, extracurriculars, and networks. This can lead to better job opportunities and, subsequently, more wealth.

6. Network Effects: Being wealthy often means being plugged into networks of other wealthy and influential people. These networks can provide information, opportunities, and partnerships that can further increase wealth.

7. Inheritance: Wealth is often passed down from one generation to the next, ensuring that the beneficiaries start with more resources than others.

8. Risk Tolerance: Those with more financial cushion can afford to take bigger risks. While not all risks pay off, some can result in substantial rewards.

9. Psychological Factors: The confidence and mindset gained from having money can lead to behaviors and decisions that further generate income or protect existing wealth. For example, a person with substantial savings might be more willing to invest in their own business or education.

10. Regulatory and Tax Environments: In some cases, tax laws and regulations may favor the wealthy, allowing them to protect or grow their wealth more easily. For example, tax codes in many countries have provisions that are advantageous for investments, real estate, or certain types of income over wage income.

11. Barrier to Entry in Certain Industries: Some industries require substantial capital to enter. Those who are already wealthy can enter these industries and reap the potentially high rewards.

12. Asset Appreciation: Assets such as real estate, art, or stocks often appreciate over time. Those who can afford to hold or invest in these assets benefit from their appreciation.

However, it's worth noting that there's a complex interplay between these factors, and wealth accumulation is not guaranteed even for the rich. The economic environment, personal decisions, market dynamics, and a degree of luck all play a role.

Additionally, the statement "the rich get richer" can also be a point of contention in debates about income inequality, fairness, and economic justice. Many argue for policies to reduce the widening gap between the rich and the poor, pointing out negative societal implications of extreme wealth disparities.