It's not jsut the tube though. I was 40 miles from home and 20 miles from civilization and 20+ miles to the nearest bike shop. If I gave that guy my tube, I would risk stranding myself if I got a flat.

That guy took a car ride home and it costed him $100. That guy chose to ride into the sticks with only one CO2 so there was a real risk that he'd have to summon a car to take him home.

I chose to carry a tube to mitigate the risk of having a call a car. If I gave up my tube, then it feels like the risk of having to take an expensive car ride home is just transferred to me. And that is the part where I am uncomfortable with. I did not get a flat tire on the way home, but I also do not poses the powers to predict it.