Monitoring my electric and gas bills now as an adult and I get it. It’s not too bad going from 65 to 68, but 65 to 90 would use up a lot of electricity in my case (and prior to my HVAC upgrade, uses gas which is cheaper but dries me out more). I’ll still let guests do it to some degree, but we’re talking a few dollars a day in the extreme. A month of my kid not touching my thermostat is equal to my kid getting a modestly priced video game.
Granted, I’m also the type to walk or bike a few miles instead of drive to avoid a few dollars in gas and maintenance costs. I’m not ecologically friendly, I’m just stingy.