Because I choose not to fly low level across a large distance of water in a SEP.
It is a personal choice
but as you suggest you are in fact making this choice purely on grounds of safety. In fact the choice you make gains you a better service than those beneath you (because they are not qualified to climb into the airways).
The guy beneath you chooses to declare IFR because he believes in consequence he is more likely to get a RIS, than those on VisualFlightRules, and he makes this choice because he considers he is less likely to have a collision when IFR with a RIS.
The chances of a collision and an engine failure for this sake are not very different.