When I say the floor is comfier I mean it, no mattress or anything, and at most I use the support of a pillow or two. I live in an area where it's consistently hot, where it really only drops below room temperature in the winter, so for a good majority of the year so falling asleep is difficult. The hot weather makes couches and blankets pick up heat too easily. Even if I lived in a cooler area I would still detest beds and couches since I tend to find soft surfaces to be rather unpleasant. On the other hand, the floor, which usually carpet, usually has a hard surface with a consistent temperature that makes it enjoyable to rest on. I like hard wood floors too since the cold feeling is nice I find to be pretty refreshing, but not in a thirsty kind of way if that makes sense.
After my spinal damage from a crash, I can't lay on the hard floor any more. I have bones and muscles shift around in weird ways that seem to stay out of place. In many ways, my chronic issues are like someone that is much older than myself. You're likely to experience similar at some point much later in life, when your body physically needs that extra support to stay in one piece effectively.