It's not that people aren't believing you or that it's not true, it's that it doesn't apply to the conversation at hand and so completely misses the point that it's kind of baffling that anyone would arrive at your conclusion that it's this simple with a straight face.

The reality is that it isn't hot vs cold, it's all of the things climate change are affecting -- hotter weather, yes, but colder weather too, less predictable weather, more extreme/frequent storms and natural disasters, crop failures, the associated geopolitical fallout, loss of habitable land, water shortages, and the countless downstream effects of all of the above and more. And I'm pretty sure that all those things are deadly.

Also, putting literally all of that aside, hot weather kills people too, so if it even were as simple as "hot vs cold," more frequent and hotter hot weather would also kill more people too. Look up wet-bulb temperature if you'd like to find a new source of nightmares.

The fact that you apparently don't see any of this and just think "hot = better because more people die from cold weather than hot" is why you're getting downvoted to oblivion. It's a surprisingly braindead argument even by HN's all-too-frequent "can't see the forest for the trees" lapses in judgement.