And you are right - but poor people _want_ to have material luxuries, by and large, so we should consider what we want our equilibrium state to look like.
Personally, I'm hoping for "8-10 billion people eating low meat diets, living in well insulated homes powered by renewable electricity, in places where they can walk, bike, or take public transport for almost all of their daily needs, and working a 20 hour (or less) week, with the remainder of their time filled with their friends, families, creative passions, and any other joys not yet comprehended"
but it doesn't seem like that's where we're headed.