Goodness, @Daftbag1, I fervently hope that no grandchild of mine will ever give me such a horribly pious lecture!
But if they ever did, I’d tell them that
a) the trees that are turned into card are a crop, like any other, which will be replaced,
b) that softwood trees like that actually use up a great deal of CO2 as they grow.
And c), it’s perfectly possible to buy recyclable cards!
All mine this year were recyclable, ditto the vast majority of those I’ve received.