Fortunately, there is a way to mitigate this investment risk.
Pound cost averaging involves “drip feeding” your capital into the markets over time, buying shares and other assets at whatever price they stand at the time of the investment.. This is a natural way to invest for those with no lump sum to commit, but it can also be a powerful approach for those with such a sum. It likely means that your gains will be slower or perhaps more modest, but the risks or angst involved with lump sum investing are typically greatly lowered.
Let’s consider the £50,000 example once more. Instead of investing it all in one go, you choose to instead commit £3,000 each month over 2020 and into 2021. In this scenario, by the time March comes along and the markets crash, only £6,000 has been invested and thus exposed to the volatility. The rest is safely held elsewhere (e.g. in cash). In March and April, however, you also invest £3,000 each time - buying stocks “on the cheap”. As the markets steadily climb back up during the following months, the losses on your first £6,000 investment start to recover. At the same time, the investments you made during the rally rise in value - growing the value of your portfolio.