Are there people who cannot handle living in hot humid tropical climates? People who will get constantly sick?

Yes.. I am the example.. I always get sick every time I stay in hot humid tropical climates.. I alWay suffers bronchial allergy

Yes you can get sick, not from the humididy and such but the climate itself. I live in a hot, humid tropical climate(Florida Keys) and I went to southern california for the first time recently, when I got back home from my trip I got sick. A friend who is a teacher also got sick, she told me it was because of the climate change...But You wont CONSTANTLY get sick.

Humans are adaptable. That is how we have survived 2 million years. When a person moves to a new climate, they feel uneasy for a few weeks and then they adapt and feel just fine. We tend to judge how we feel for the first few days and think this will never work, but that is wrong. The earth will still have millions of hectares of land too cold for human habitation if the worst case scenario actually comes true.

I am Croatian and find it very uncomfortable to live in warm/hot places. I like cold places/lukewarm places. I also have a little case of asthma so it is very unhealthy for me to go outside if it is very humid.

Yes. Definitely. There are some people who have less or very little sweat glands on their head. This is where the major part of cooling of the human body is. If you cannot get that heat exchange your body becomes over heated and even sometimes death.

mostly white fair skined people