The benefits of diversification across asset classes cannot be understated. Over the long-term diversification not only smooths out rough short-term variations in returns but also helps as cushion the blow when one asset class under-performs. With that said, the following 2019 Vanguard Index Chart and table from Vanguard Australia shows the advantages of diversification over the long-term using Australian stocks and other asset classes:

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Source:  Stay The Course – 2019 Vanguard Index Chart, Vanguard Australia