The stock market is a horse race where you are allowed to place your bets even when the race is half over. You are allowed to bet on the leaders. They can always stumble or be overtaken, but there is a large enough pack that a bit of prudent diversification has a high likelihood of success.
The individual investor does not have the problems of the fund manager, who must find a place for many millions in investment and is forced to put money on the laggards. ETFs are supposed to provide less risk, but they ensure that the profits of the horses in front are dragged down by the losses of many others coughing in their dust.