You can. If you're in the US, sign up for a brokerage and park your uninvested cash in a government securities (primarily US treasuries) invested money market fund [1]. You're now backed by the Federal Reserve instead of FDIC and their oversight of fractional reserve banking [2] This is a nice hack around the fact that the Fed won't approve a Narrow Bank [3].

[1] https://www.investor.gov/introduction-investing/investing-ba...

[2] https://archive.is/HXfvw (Bloomberg: Matt Levine: Banking Gets a Bit Narrower)

[3] https://www.chicagobooth.edu/review/safest-bank-fed-wont-san...

(not investing advice)