Up to you. I never understood that attitude, people act like air travel is the only one subsidized, meanwhile (at least in Germany), everything from tracks to new vehicles, tickets (like the 49€ ticket) to covering of losses is subsidized by our taxes. And they are still way too expensive.

Meanwhile, airplanes are actually shockingly efficient per kg/km travelled - the train is just even more efficient. Most of the airlines even give you an option to offset your CO² footprint for the flight. Taking the difference between train and air travel and donating it to a worthy cause would likely be the most valuable option from a world saving standpoint.

But that's neither here nor there, I understand it's about feeling good as much as it is about efficiency.