Why don't some people wear winter clothes in the freezing cold weather, despite being aware of the consequences?

Thanks for the answers!! I've seen pictures of people and people in real life in Winter in the Southern states on a typical winter day with a high of around 50 and low of around 30, in which some were in their warmest layers, while some in short sleeves and shorts and nothing more than a hoodie over their short sleeves or even with no hoodie.

I am from the South, but I like the cold. The coldest temperatures in winter where I live generally are around the teens or lower 20's and I have a friend who is from New England who doesn't classify weather as officially cold until it gets to around 20. Therefore, most days in winter where I live when the high temperature is around 40-60 and low is around 30-40, he is in generally short sleeves, shorts and hoodie. He doesn't wear a winter coat unless it's below freezing.

As in a winter coat, I mean a fleece or puffer jacket, as in he could get by without unless it's freezing and also he wears shorts if it's 25 degrees in the morning, as it will get to at least 40 later on generally and he could get by easily.