Shock! Possible zero return in decades

Very shock to read this chart! 

At first sight, we may happy that the stock market keep growing, if invest in index ETF, we will gain eventually. But if we zoom in, shock to realise that we may suffer 30-40 years zero return if just buy & hold! How many 30-40 years can a person have?  

For me, after 13 years investment, the overall return is -11% (not annualised). 

Need to think more carefully!