The total value of 401(k) accounts in the US is about $3.8 trillion. In normal times, that's roughly 16 months of federal spending. Right now, it's less than four months. The government doesn't need our retirement accounts; it owns a printing press.
The financial system benefits greatly from this source of liquidity, and the banks are the ones that got Biden nominated over Bernie and Liz (they also approved of Harris, or else she wouldn't have gotten the VP nomination). So as long as Wall Street benefits from our retirement accounts, .gov won't be stealing them... well, not directly. They will get taxed into oblivion upon withdrawal, or inflated away to nothing.