Here's the thing that I didn't really consider when I was younger. We all know when we saddle up in a piston single that there is a slight chance of an engine failure. We also know that if the engine should fail, there is a chance that we may not survive the off airport landing. But we're taught to prepare for that off airport landing from very early in our primary training and if we hang around the airport long enough, we'll probably meet someone who has experience such an off airport landing and walked away without a scratch.
All of that tends to make us feel very safe about getting into a piston single. But the thing that I never once considered the few times I flew over Lake Michigan and Lake Erie is that an engine failure there, however unlikely, would be the equivalent of a death sentence for killing the Governor's daughter. IOW, a death sentence with very little chance of the Governor calling at the last minute to give you a pardon.
If the motor quits, you're going in the water. And if you go in the water in the middle of any of the great lakes without survival gear, you're dead regardless of the time of year.
But lest this turn into a flame war, I respect the choice of those who accept the risk and cross without gear. And I expect them respect my choice not to.