Even if it is truly too late to avoid climate catastrophe, I believe there are things individuals can do to make life on Earth better now that also help slow the destruction of the planet. I'm vegan, for example, because I want to reduce the unnecessary suffering and death of my fellow animals. Avoiding the products of animal agriculture also lessens the burden on our shared Earth.
I'm aware that just being vegan isn't going to save the planet by itself. A single vegan who lives in a mansion and flies in a private jet is going to have a bigger environmental footprint than a large family whose members consume some animal products but live in poverty with very little space and resources. However, neither of those scenarios apply to me.
Speaking for myself, I would like to think that my individual actions make some positive difference to the world, whether or not planetary healing can happen in my lifetime. Otherwise, I just feel hopeless, and that feeling will lead to apathy and even more wastefulness. I don't think that mindset would be helpful to anyone.