I don’t disagree that I could survive without the comfort, and I would probably get used to the discomfort after a while and wouldn’t think about it as much.

What I don’t understand is why it is bad to have gotten used to modern luxuries, or why my life would be better if I gave those up and lived more primitively.

There is a reason we created all of these creature comforts for ourselves, and why very few people actually go through with giving it all up and returning to a more primitive lifestyle. Those things are nice, and most people want them. That is why they were invented in the first place!