Yes, my understanding is that the cost of missing out on those companies that are providing the returns is much more costly than investing in a company that is

Yes, my understanding is that the cost of missing out on those companies that are providing the returns is much more costly than investing in a company that is NOT generating those returns. In other words, the risk is to miss the winners, not that you will invest in a loser. The problem is that it is very hard to predict the winners, so it is best to invest in all companies to make sure you have the winners