It's immaterial whether Gabon has a low population density or Ethiopia has a large population, there are myriad other factors influencing progress and sustainability. Even if it was determined that living in an area with less people was better, you have no business in either Ethiopia or Gabon, and even if they had a good balance of lifestyle, there's no saying a stranger's sudden presence will do anything to enhance that, or even complement that.
There are so many factors causing a population boom and equally so a serious decline. It doesn't do to generalise. I'd venture that administrations at either end of the scale have it as a factor in their determinations.
Largely agrarian societies have receded, and land needs are contracting with the change.
People have shown they're willing to crowd around in places that have otherwise plenty of space. Convenience and particular proclivities dictate a postcode as much as any other factor. Having lived in isolation, it had its shelf life for me. Chiefly childhood.