I don't like this example, because it ignores that normal people take planes, too - sure it's less frequent, and it's usually public transport-style as opposed to just being one billionaire and their entourage per plane, but there's also just a lot more normal people than billionaires. Not to say that the pollution made for billionaires' personal lifestyles isn't massive or that rich people's economic and political activities aren't the main driver of climate change, but using such an obviously bad example makes it too easy to dismiss the general sentiment of the joke. If every non-billionaire stopped taking plane rides, it would make a difference for climate change - the issue is that rich people do their hardest to make sure that something like that doesn't happen. At least not until all the non-millionaires are so poor that they can't afford to travel anymore.