I live in a pretty hot climate, but it’s only really unbearable at times due to shoddy building and bad urban planning. Even then, summer can be difficult.
I can’t imagine what it’s like on the equator, especially in dense urban centres. What’s Mumbai, Bangkok, or Singapore like at the height of the wet season?! How do millions of people function day to day?
Dry heat and dry cold are much better to deal with than wet heat and cold.
Russians who strive in -30°C get cold in the 0-5°C wet mist that is much of Central Europe during winter.