I have uninvested cash sitting in a tax-advantaged retirement account that earns interest in a government money market fund. Right now, it's roughly 4%. Hence, any premiums earned on cash-covered puts are a bonus on top of that. My brokerage liquidates the money market fund automatically when purchases are made.
On March 18th, I sold a put, with strike price of $500, expiring 28-March, for $1.21. Nothing impressive, but a little something to do while waiting for the price to fall. Yes, my calculated IV for BRK-B is $500. But that's me.