Human life tends to flourish in the balance.
Most of our planet fits that description. As long as you stay away from the South Pole and don't fall into a volcano, Earth is a pretty comfortable world. Space is a radiation-dominated environment. Objects heat up by absorbing sunlight and they cool off by emitting infrared energy, a form of radiation which is invisible to the human eye. As a result, insulation for the International Space Station doesn't look like the fluffy mat of pink fibers you often find in Earth homes.