Final answer:
Investors cannot attain a portfolio below the feasible set because they cannot eliminate risk entirely. Financial investors face challenges in predicting future returns, which is why attempts to outguess the market are often unsuccessful.
Step-by-step explanation:
Investors cannot attain a portfolio below the feasible set or opportunity set because they cannot eliminate risk entirely. Past performance of a company does not guarantee future profits, and high profits do not necessarily translate into high capital gains. Despite attempts to predict future returns, the majority of financial investors cannot consistently outperform the market average.
Financial professionals face challenges in forecasting the markets due to the complex nature of stock prices, which are influenced by various unpredictable economic and non-economic factors. Moreover, investors' efforts to diversify further have limits; there is a minimum level of risk that cannot be diversified away, known as systematic risk.
Overall, trying to pick the stocks that will significantly gain in the future is fraught with uncertainty, making it difficult for investors to achieve returns that are not already reflected in the current opportunity set of investments.