The stablecoin DAI is as risky as the US Dollar, which it is pegged to.

False. DAI is an asset backed stablecoin, with ERC20 tokens as collateral. Since it has these ERC20 tokens as collateral, DAI is riskier than the USD, since these tokens are more volatile. In addition, the USD is regulated by a central bank, which has proven to have more experience in regulating assets, making USD less risky than DAI.