Yeah, if he keeps $1 million in a checking account, we already know he's an idiot :-)
But that raises the question of how much in relatively liquid cash is sensible to keep around. I have about $120k, about 3/4 in CDs of various maturity and about 1/4 in shorter term savings. It only generates a few thousand dollars/year in interest, but it means I can easily buy a car with cash if need be, or pay for major home repair (new roof), or even buy a piece of undeveloped land if I want to (thinking ahead to where I might want to live after I retire). Or, heaven forbid, manage an unexpected spell of unemployment.
Most of my savings are in stocks, but I sleep better with some cash.