$M, not too difficult in US for the average

The median income in the US in 2015 was $55,775; there are places where it is more than that. 

It is also true that average Americans cannot save enough to fund their retirement. This is why they also end up working in places otherwise they would not have liked to. This is also why they are sort of forced to take up work for longer years than they would have otherwise liked to. What a life! Even a masochist wouldn't like it. 

Someone said it long ago: Twenty years from now you will be more disappointed by the things that you did not do than those you did do. So throw off the bowlines. Sail away from the safe harbor. Catch the trade winds in your sails. Explore, dream, discover. 

It is an apt statement. Life is too short to stick to the comfort zones. Nevertheless, it is not very difficult to come out of it; neither does it take too long. The key is to become financially independent. Note that it is not being rich, which is actually relative. Someone with $500 k is richer than the one with $100 k; one with $1 b is richer than the one with $100 m. Talking in terms of the rich is not only useless, but also stupid. 

What we need to attain is financial independence. It is always measured in terms of how much cash one has compared to one's expenses. The higher the multiple, the higher the assurance. Someone with $100 k in financial assets and annual expenses of $10 k is wealthier than someone with $500 k assets and annual expenses of $250 k. To become truly financially independent, one needs to increase the multiple. 

There are only two ways to achieve an early financial independence: Increase income compared to expenses, or Decrease expenses compared to income. For most, it is much easier to do the latter; yet, they do not realize it. For them, life is to enjoy the moments on splurge. Little do they know that there is plenty of fun in delayed gratification. 

So how does an average person, employed with an average salary, become financially independent? If the two conditions are fulfilled, it is not very difficult: One, restrain; control; and behave. Two, invest savings in equities, preferably, in the S&P-500 index fund. 

In January 2000, S&P-500 was at 1394.46; in December 2016, it was at 2238.83. A 2.82% annual return over 17 years is no fun. Yet, the average employee could have become a millionaire by that time. 

It is because the markets are inefficient. They fumble on occasions; act irrationally at times. That's how they provide opportunities to the average employee. In February 2001, the index fell over 9% from the January 2001 value. 

Sure one could have bought in March 2001 and sold in April 2001; again bought in October 2001 and sold in November 2001; and so on. But we are talking about the average employee. In fact, here, we should be talking about everyone. It is very difficult to time the market on a consistent basis. Let's keep that story for another day. 

I am going to talk about the average 25-year old couple earning a combined salary of say, $50,000. Not very unlikely for the average. They are ordinary individuals, engaged in ordinary employment. How could they become financially independent? As we noted, it is easier to cut expenses than to increase income. 

If the couple saved and invested $2000 per month, which is $24,000 annually, in a low-cost S&P-500 index fund from January 2000 until December 2016, the total investment would be $408,000. Another way to see it is to keep one salary for living costs, and invest the other; there is not much excuse. Remember the buzz words: restrain; control; behave. It's possible. The investment value would be $707,000 as of December 2016 before the fund expenses, which are not too high in a low-cost fund. So the couple would be worth $707 k at age 42. The annual return changes from the paltry 2.82% to a more reasonable just over 6% due to the dollar-cost averaging, which happens thanks to the market inefficiencies. I have not included dividends, which if reinvested, should increase returns. 

They might say, the salaries weren't that much in 2000. It turns out that the numbers are not far off. If the investment was increased by 5% annually reaching $4600 per month in 2016, the investment value would be just over $1 m; not too bad. $4600 per month translates to $55,200 annually, which is the median salary anyway.

The losers might talk about taxes, etc. Remember, though, we are talking about creating enough wealth for the ordinary individuals early so that they too can let go of their shackles, and explore life. This is to show that it is very much possible for the average. The trade-off is clear: work for someone for life, or call your own shots after 15 years.

Their behavior is more important than income they earn. Cut costs relentlessly, and invest every month irrespective of the index value. After 17 years, at age 42, the couple could have $1 m in financial assets, which would also give quarterly dividends.

With $1 m plus financial assets, the average couple could move to a place where home and living costs are much cheaper, and have a fun-filled life. Why do they have to care to work for another unless of course they actually do love it? There is a superior life outside of the Bay Area and Wall Street too; and it can be more purposeful.

And now for the not-so-ordinary. If the couple can save $5000 per month, the investment would be worth $1.7 m. There are plenty of households whose annual income is $120 k. $5000 per month with 2% annual increases, i.e. $7000 per month starting 2016, would turn into investments worth $2 m.

Again, they might talk about the hindsight bias: where're the future returns?; Europe and Japan are already down; China is on the way; the US is not going to be an exception. Heck, these are the people who don't want to give up on the status car, large TV, expensive cell phone, fancy gadget, and those regular $5 coffee twice a day. If only they learn to defer their gratification, they would have to work, without choice, for only a maximum of 15 years.

But, heck no; human behavior has reasons that reason cannot understand.