Investors are said to achieve far less in returns than the markets in which they invest. How is that possible you may ask? Typically it is down to investor behaviour. Investors get blamed for doing silly things when it comes to investing, however my take is that it is the financial professionals who must shoulder the responsibility for it.
This is not to suggest that the advisors/planners that might assist investors have total control over what an investor does, but I do believe that if an investor is engaging with an advisor/planner that that professional has a duty of care to let that investor know how investments have worked since 'time began'. Without this knowledge then it is only utterly natural that an investor will succumb to fear and do something irreversibly costly which will have a lasting negative impact on their future.