I think in the US at least, travel has an even deeper aspect of ritualized behavior or religiosity in the positive sense of those concepts. A pilgrimage for people who don't believe in anything.
Even someone who takes a 20 hour flight to take photos for Instagram is having a unique life experience. They are going to have experiences worth telling stories about. Certainly more than the person who doesn't leave the house.
I quite enjoy traveling and fly about 50,000 miles per year. I take offense to your sentiment. I have as much right to travel as anyone else. We need to live and let live.
You haven't given the number of how much CO2 people use to live, only what the sustainable number is, so there isn't enough information to make any conclusion.
Sounds like that number just takes the CO2 that the us produces and divides by population. It would be agreeable if the wealth that came from that CO2 production did also was similarly distributed, but since it's not, that's not really how much your every day joe produces to live. It's what is produced to put another billion dollars onto a company's books.
Even someone who takes a 20 hour flight to take photos for Instagram is having a unique life experience. They are going to have experiences worth telling stories about. Certainly more than the person who doesn't leave the house.