Time to put this simplistic idea to the test with some science and rational thought ...
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A couple of degrees milder winters is not the solution, but hey, some people seem to prefer to die from tropical decease, than to isolate their house better, wear more suitable clothing, and save on heating expense ...
Yes, indeed, some people seem to prefer to have less money than other people. Sheesh! Seriously, Bart!?
The underlying logic in the stats and statements that you quoted is so far from a rational thought that it is mind boggling!
Southern European countries have a higher rate of winter deaths than northern ones!? And that is a proof that it is not low-temperature related? Really!? Who would have thought? Harsh winters are the norm in the north, and an aberration in the south. When something is the norm, you prepare for it. When I was living in Barcelona, a vast number of older apartments did not have any heating provisions. The same with some houses here in Florida.
All other factors but temperature are irrelevant. Loneliness, social safety net, inequality, etc. are the same all year long. However, unexpected, unprepared-for lower temperatures make poverty and illness harder to survive.