Yeah, I think these rules (US) were made by people doing the math, without considering reality. It’s real easy to set aside a good amount to retire, as long as you set aside the recommended percentage throughout your career.

Of course the reality is that most of us will never do that. Many of us will get divorced and lose half what we put aside. Many of us will have financial emergencies such as medical emergencies, or being out of a job. Many of us will just be scraping by and can’t afford to set aside that much of our pay. Many of us just won’t have the perspective to be willing to set aside money for retirement many decades away. Many of us will live through times when our investments lose significant value over years. More importantly , most of us will hit those conditions sometime in our career and the basic premise is just not realistic. At least as importantly, with so much dependency on compounding returns over decades, there’s no way to recover when all those rosy assumptions don’t pan out.

I’m a good example, where I make a good income and realized the importance early on. At the beginning of my career I was able to daydream about my expected millions to retire. A few decades later and I’ve hit all of the above so am not even close. Even now as I panic about how soon I need to retire and how little I have set aside, and am making renewed effort, there’s no way to make up for all those missing years of compounding returns, and there’s only so much I can do while paying kids college expenses.