By cruise control “toggle” I mean the on/off switch that gets the cruise control ready to be set, not the set button itself.
Safety issues of accidentally hitting the set button aside, can leaving this toggle on all the time do any damage to the car?
There’s a marital debate hanging in the balance. =)
In as simple terms as I can, no.
To further clarify ptptrspp’s answer, no.
Agreed. Actually toggling it can do more harm as you eventually wear out the switch 
I agree with the others. Unless you have a malfunction of some kind, leaving the cruise control on (but not activated) will do no harm to your car.
Here’s another vote for no possible harm.
What harm is one of you claiming will occur?
Here are the two things you should remember if you really want to "not hurt your car’. Do not operate the engine for even 15 seconds with the little red oil can light on and do not operate your car at all when the temperature gague is in the red.
I cannot envision any sort of damage that can happen to your car by doing what you describe.
OH yes, I wanted to add, you can drive with a flat tire to get the car off the road.
Remember you can’t drive with the oil can light illuminated, not even to “get to a place where it is safe to stop” and the same thing goes concerning operating your car when it is overheating.
I leave it on (CC enabled) all the time.
This can cause no more harm than leaving the ‘Scroll-Lock’ key lit on the computer.
How long could you stay polite when explaining this when you had several customers waiting for your attention? I know some who approach sainthood would say “as long as it takes”