Why do some many people have absolutely no problem to take unnecessary flights?

I know of course that most of the time it’s just so much cheaper and more convenient than f.e. taking the train or driving with your car but I still wonder how many people will take the train for distances under 2 hours.

My last flight was back in 2018 and I still feel actually guilty because of climate change and my carbon footprint, but it seems that some people don’t even realize their own impact on this.