We are creatures of habit. When you go to your favourite coffee shop, you expect to get that same coffee, made by that same barista. When you go to that Thursday morning yoga class, you expect to see your favourite yoga instructor. When someone you have never seen before skips into the room and takes the instructor mat, you sigh a little and shake your head before getting on with the class.
When you invest, you expect to get the return due for the risk taken. An example: if you buy an index fund or ETF tracking the MSCI All Country World Index, you will expect it to give you an annual return in-line with its long-term average (minus costs). Though the long-term average is an indicator of what to expect in the long-run, there are very few single years of return that will fall anywhere close.
MSCI All Country World Index annual return minus average annual return (USD)
In the 23 years from 1995 to 2017, only 6 years fell within a 10% range (+/-5% radius) of the long-term average annual return of 9.12%.
Furthermore, the best and worst 12-month return in the period ranged from +59.0% to -47.9%. This is an enormous dispersion of returns.
Each year is made up of 365 days of ups and downs, sweaty palms, hair-raising news, and your beating heart. It is not easy to patiently allow the fluctuations to work themselves out.
Diversification does remove some volatility, but if you expect to achieve anything close to the average annual return every year, you will be sorely disappointed and should probably steer clear of equity markets.
Ignore the desire for gratification in getting what you expect and try to ride out the market fluctuations, knowing that you have positioned yourself for long-term investment success.