the meaning includes the irrelevance of risk preference and the diversity of investment portfolio.

1. Irrelevance of risk preference: Under the assumption of complete market, investors' risk preference will not affect the choice of optimal investment strategy. No matter whether investors are risk-averse, risk-neutral or risk-seeking, their optimal portfolio can be constructed by linear combination of risk-free assets and risk asset portfolio.

2. Diversity of investment portfolio: Investors can spread risks by investing in various risky assets, while risk-free assets provide a benchmark for risk adjustment. This decentralized strategy can maximize the utility of investors and reduce investment risks.