See now laziness is a perfectly acceptable reason for almost everything 
For me, principle is that I’ll leave the heat off until I absolutely can’t stand it. I was raised to throw on some warmer clothes before I turn on the heat. It’s a financial decision before anything else.
That said, I’m the opposite about the A/C. I’ll run it damn near anytime of year, especially since my window unit provides white noise and helps me sleep.
When I don’t turn my heat or AC on, it’s not based on principle, I’m not trying to save the Earth or anything. It’s a financial decision first, environmental benefits are just a good side effect.
I remember in college when October 15 would magically arrive. We could no longer use the A/C because it was disabled. We could turn the heat off, but had no way to cool the unit for those sunny and warm Indian Summer days that crept into the 80s. Made it quite miserable. Lots of forbidden alcohol was used to cope. Spring wasn’t a problem, by the time they enabled the A/C, it was still easy to manage temperature by opening/closing windows.
Now, the temperature of the house decides if the heat is on or off. I try to keep it off early/late in the season, because I don’t want to spend the money. But I will turn it on for a little bit to nudge the temp up, and then turn it off. Others in the house get acclimated to the temp dropping back down, and it works. I am the master of the thermostat in the house, not because of a rule, but because everyone else refuses to mess with the damned thing. I keep them froze in the summer at 68~69 degrees, and they complain but won’t do anything about it. They’re cold this time of year, but won’t do anything about it. When the heat does go on, 69 degrees is the top they’re getting from me.
I loathe such people and businesses who do such. A special place in hell should be reserved for them, with no AC! My ass has been frozen off this fall.
I make a decent wage as does my husband. However, I don’t like to spend a lot of money on heating or cooling.
I spend about 1200 less a year in utilitie costs because I put on a sweater or snuggle with a cat and blanket. It’s all about priorities.
Come to New Orleans and all will be clear 
Without A/C running, your paper towels, TP, and clothes dampen just from the humidity in the air.