.
Every broad market index investors knew. Is well-documented. See chart below.
Most of us think we are very smart, much smarter than average Joe, so we stock pick. Those lucky ones (random) e.g. me 
can do humble brag and tell how they use analysis (fundamentals, identifying moats, EWT, cycles, time in market is better than timing the market, algorithms, AI, whatever reasons) to achieve the result. Some even try to sell stock advice, publish books and run hedge funds. In truth, pure luck, a random event. Survival bias talking.
Ofc, not all think they are smarter than the market. Read a few articles, many wealthy people knew they are not. They put their money in safe assets and a few % in stock picking/ trading just for talking points during social parties and casual talks.