I retired 2 yrs ago, I had 4 holidays on 4 continents in 2019-20 before lockdown. I now have 5% more in the retirement funds than before I retired. OK at one pount a year ago, I had 20% less, but that was peak pandemic and its all recovered now. I keep 2 - 3 yrs worth in cash so I didn't have to cash in any stocks while they were low.
Basic message, spread the investment, don't trust anyone who says "Pick this stock" and be prepared to ride out the troughs. Sure beats 0.39% in the average cash savings account.