It is worth the effort if you can do something which might have only a visible effect in 300 years. Time is very relative. If you can plant a few seeds to make this world thriving, peaceful and joyful it is worth it.
If you can be kind and compassionate to a few other beings that is like seeds for the future and may be somewhere at some days it will grow, may be not, but nonetheless it is worth the effort.
Dreaming and visualising alternative possibilities and ways of living is like carving out a future life. Carving is a slow process. But like slow food it tastes really good. And when it will have an effect somewhere in an unknown future it is worth the effort.