It doesn't. That's the golden lie. The truth of trickle-down economics is that it isn't real. It's just clever phrasing from metaphorical dragons who get to hoard their treasures at an increasingly rapid pace.
Here is my thought experiment so far:
I assume an investment yield of 10%, however, asset classes vary. It is also a simple number to work with.
3% inflation. 3% dividend. 4% growth. I simplified it on the idea of 7% return after inflation.
10k per year. 40 years. 7% yield. About 2M. So 10M is out of reach for most people. Somebody has to be very lucky investing or build a business to get there.
Also, whatever habits mentioned previously got to 2M do not change when you finally get there. So the person that does get there is unlikely to just quit working and investing.
Going back to the thought experiment and the person with 10M in invested assets living off of 300k, the growth after inflation is 4%. The person saving and investing is making 7%, so there is a point of catching up given enough time. However, we do not have infinite lifespans. This also means that these assets pass down somewhere, whether or not we reproduce. Assuming that we do, then I will work with a reproduction rate of 2%. This corresponds to a doubling (generation) in 35 years.
I am really sorry about having trouble composing a discussion that makes sense. The thoughts I am trying to compose are greater than my capacity to articulate them in the time I have given myself. The big issue is multiple subjects.
So why would you need that much? Security presumably which if was shared around a bit more wouldn't be such a concern.
It is interesting we both assumed the denomination was US dollars. The best response I can think of for you is uncertainty. The $10M I mentioned yields $300k. This pays for health coverage. Now where am I going to live and what am I going to eat?
So one uncertainty is the cost of health coverage, which is rising much faster than inflation. I think housing and rent are also rising much faster than inflation.
Another uncertainty is the (stock) market. The 3% is what I would pay myself if I was told to retire with a bunch of assets. I can also take a reciprocal of my current life expectancy. So in this case, I gave myself 33 years, which is slightly low given my current age. However 3% is a nice round figure to work with. It is possible the next year, the (stock) market goes down 60%, so the $10M portfolio is now worth only $4M, and the $300k in income is now only $120k. If I reduced the numbers by an order of magnitude, $1M becomes $400k and $30k becomes $12k and I go homeless and cold and starve.
I can get around this problem with diversification. However, interest rates are near zero, especially when factoring in inflation. I can get around this by keeping some cash, very similar to the previous sentence. The five-year volatility is much less than the one-year volatility.
I also did not mention real estate.
I sense..... that somebody here will give me a big education on investing and asset classes and diversification.
I still never addressed the OP question.