Textbooks teach us multiple concepts that help us understand the principles of investments. Particularly,

Textbooks teach us multiple concepts that help us understand the principles of investments. Particularly, many agree upon starting investing early and regularly.
Let’s read the following and share your opinions on them. Do you agree with them? Why and Why not? Can you share your insights on other principles of investments?
Jack Bogle (The founder of Vanguard mutual fund company) introduces an invaluable experience from one of his clients. One person started his investment from 1970s and achieved the value of his portfolio of $1.25 million by 2005. His income was never more than $25,000 per year in his lifetime. How was that possible?
Did he learn sophisticated investment skills? Did he have rich parents?
The magic was
to have the Keepers’ mindset (refer to the first Discussion Topic), and
to start investing early and regularly for a long time.
How does it work?
Since he has the Keepers’ mindset, assume that he saved about 27% of $25,000, which is monthly $563, and invest monthly the same amount in the index funds which earns 10% on average for 30 years, then the balance becomes $1.27 million.
 
Some background concepts if you needed:
Start early: https://imealliance.com/learn/investment-fundamentals/the-power-of-investing/content/default.fs (Links to an external site.)
Invest consistently for a long time (Dollar cost averaging): https://maximizeyourmoney.com/investing/everyone-should-know-this-the-magic-math-behind-consistent-investing