So I'll just note a few things:
1) You can clearly see the Great Depression and 2008 in here, so I'm just going to ignore those.
2) The other really nasty period for market returns was during the 70s oil crisis and subsequent high inflation period.
It also notably marks areas "slightly above inflation" as red, which are not periods where loses would occur (though, yes, the gains would be basically flat). This strikes me as an odd choice and a misleading one that makes the historical analysis look worse than it actually is.
Yet despite that, the majority of that chart shows returns moderately above inflation, sitting in at around the 4% safe withdrawal rate.
I personally don't view this as justifying the claim that individual investors need to worry about market timing. If anything it reinforces my view that they shouldn't because no one could apriori predict the kinds of events that led to the red areas of that chart.
But what's the relevance of that? When the next bubble pops, whether it be in two weeks, two years, or a decade, you and your investments are going to experience it. Some of those red splotches go on for twenty years.
As for why doing "just barely better than inflation" is marked as red, the chart accounts for inflation, but it doesn't account for a time value of money. Putting $1 dollar in the market to get $1.04 back out 30 years later is not a positive investement.
"Yet despite that, the majority of that chart shows returns moderately above inflation, sitting in at around the 4% safe withdrawal rate."
Which is why it is generally not a terrible idea to invest in the stock market.
But this is basically a goal-post move relative to the "common wisdom", which presents it as a done-deal that the stock market is always a good investment that produces a ~7% return every year. It won't matter to you that it tends to generally produce a relatively decent return over 50 years if you are currently, unbeknownst to you, at the beginning of one of those big red areas that may stretch down for decades.
Look at the stock market as it stands today. I will not tell you 100% that we are in such an area; internet commentators have predicted one million of the past 3 recessions. But I will tell you that it's an awfully plausible story.
This is not how annual returns work. If you put a $1 an average return was 4%, you will get $3.25. And if you put it in a tax deferred account or did not withdraw a lump sum after 30 years, the effect of taxes would be less dramatic.
What other investment performed better over the long time? For instance, housing did not grow much until 30 years ago.[1]
All that said, it does show that the longer you hold, the more likely you are to achieve an average positive return. Note that the only negative return (again in real terms) is the darkest red.
Again, just to drive the point home, the neutral color 3%-7% return is after inflation. If the long-run average inflation is 2%, then this is 5%-9% average annual return which almost exactly tracks the common assumptions surrounding long-term buy & hold.
This is what happens if you do all your investing in one big lump sum, e.g. putting one dollar in the market in 1970 and getting out less than a dollar (after inflation) in 1985.
Outside of getting a major windfall (and not dollar-cost averaging), this isn't how investing is done. Investments are typically made as income allows, over the course of decades. Yes, that means some of the dollars you put in are going to be massive losers in the long run. Others are going to be massive winners. What's important is the average over 30-year period of investing followed by a period of withdrawals spread out over another couple decades.
I'd be very curious to see a similar visualization which illustrates the same point for spans of time rather than lump-sum-in and lump-sum-out.
No, this is only true if its dark red.
The way you present the data of the graph does not represent how people invest. The average person works for ~40 years, so there are 40 individual years you could track on this graph. However, that isn't useful because compounding interest is a huge factor in returns. Another variable is people dont invest the same amount every year (typically people make more money as they age, however in most cases, compounding returns beat out income gains over the long term).
Consider if year one someone places $10,000 into the stock market. 40 years later, it grows into $48,000 (real value after inflation).
If you extend the diagonal boxes to 25, 30, 40, or 50 years, which makes more sense given how long people work and how long they live after retiring, the cumulative growth is _always_ above inflation.
Another think to remember is that if you are saving for retirement, you are very likely doing dollar cost averaging, i.e. making deposits on a regular basis. So you aren't buying all your stocks in one year, you are buying them across a multitude of years. That greatly mitigates the risk of starting at the wrong time.
For example, I started saving for retirement in 1999. It was ugly for a while but I was positive for good as of 2009, despite all the red in that graph.
That said I think there's some important drawbacks to point out.
First, that 7% figure that's often quoted is usually meant to mean nominal return. At least, that's the way it works relative to the commonly cited 4% SWR.
Second, buying and selling exactly once will greatly increase the variability of returns and also the likelihood of negative returns. It's important though to realize that this isn't actually how almost anyone invests, so just counting periods of negative returns under that assumption isn't particularly meaningful.
Be sure to carefully read the description of the graph. Every time I link this, someone assumes that the green & red indicates are the yearly returns, but the entire point of this graph is that it is cumulative. If it is red 20-30 years into the line, that means that money put it at the beginning had a negative cumulative return after 20-30 years, not that the 20th or 30th year was negative. Also observe the graph is inflation adjusted.
Yes, it's true. The idea that you can just stick your money in the stock market and see 7% returns every year is somewhere between "mistaken" and "a lie". It is not a coincidence that this idea has arisen during a time of loose monetary policy and a stock market that is being inflated by it over the course of a couple of decades. In the 1970s and 1980s, for instance, this would have been considered risible, and indeed, people did not generally value stock equities. (See the chart for why they may have felt that way.)
It is not an even remotely accurate model of the stock market to think of it as a 7% return that you can casually compound over time. Anyone who speaks of that model or uses that model doesn't know what they are doing. Your debt certainly compounds over time, but your assets can't be modeled as doing that.
A couple of further observations:
Part of the reason why the stock market can offer 7-10% gains in a year, when the economy does not offer such gains in general, is precisely that "room" is made for those gains by the years in which it loses big.
This is also part of why we have a pension fund crises, because even in the relatively friendly stock market of the past couple of decades, even these so-called professionals would blindly use a high-single-digit return estimate per year, and even in the past few years, that has been an inadequate model. The bailout they're going to need if the stock market actually crashes (popping the "Everything Bubble"?) will be literally unaffordable. (Not paying in sufficiently is also a problem, but that is also itself a consequence of absurdly optimistic models being generally accepted.)