Nice piece. Tony Robbins wrote a fabulous book called Money: Master the Game that goes into these topics in great detail. It's a huge book that is the result of his access to many of the top money managers in the world, including Ray Dalio, John Bogle, Carl Icahn, Kyle Bass and many more. He distilled their investment wisdom into a book that is fantastic but also very long (656 pages). He wrote another book called Unshakeable this is about a third of the size of the first book and therefore more easily digestible.
What we also have to factor in, at least as Americans, is that Social Security is a Ponzi scheme that will not continue in its current form for too much longer because the money simply won't be there to fund it. So for people who are at least 10-15 years away from retiring, our retirement plans should not count on Social Security. We also have to consider that our life expectancy is increasing and that we may need to set aside a substantial amount of money to cover medical expenses.
I highly recommend the books that Robbins wrote. I've read dozens of books about investing and they are among the very best.