I don’t see where you get that implication. Perhaps they’re spending a month in France rather than taking three one-week trips. Perhaps they’re living closer to town so that they don’t drive as much to get to work and their local hacker club. There’s lots of ways you can reorganize your life to be less resource-intensive without meaningful sacrifice, especially if you’re starting from the immensely wasteful late-20th-century-middle-class lifestyle.